Inline simple goog.isDef() checks

src/ol/geom/flat/flipflatgeom.js

@@ -15,7 +15,7 @@ goog.require('goog.asserts');
 ol.geom.flat.flip.flipXY =
     function(flatCoordinates, offset, end, stride, opt_dest, opt_destOffset) {
   var dest, destOffset;
-  if (goog.isDef(opt_dest)) {
+  if (opt_dest !== undefined) {
     dest = opt_dest;
     destOffset = goog.isDef(opt_destOffset) ? opt_destOffset : 0;
   } else {

src/ol/image.js

@@ -78,7 +78,7 @@ goog.inherits(ol.Image, ol.ImageBase);
  * @api
  */
 ol.Image.prototype.getImage = function(opt_context) {
-  if (goog.isDef(opt_context)) {
+  if (opt_context !== undefined) {
     var image;
     var key = goog.getUid(opt_context);
     if (key in this.imageByContext_) {

src/ol/imagetile.js

@@ -81,7 +81,7 @@ ol.ImageTile.prototype.disposeInternal = function() {
  * @api
  */
 ol.ImageTile.prototype.getImage = function(opt_context) {
-  if (goog.isDef(opt_context)) {
+  if (opt_context !== undefined) {
     var image;
     var key = goog.getUid(opt_context);
     if (key in this.imageByContext_) {

src/ol/object.js

@@ -116,7 +116,7 @@ ol.Object = function(opt_values) {
    */
   this.values_ = {};
 
-  if (goog.isDef(opt_values)) {
+  if (opt_values !== undefined) {
     this.setProperties(opt_values);
   }
 };

src/ol/proj/proj.js

@@ -148,7 +148,7 @@ ol.proj.Projection = function(options) {
   if (ol.ENABLE_PROJ4JS && typeof proj4 == 'function' &&
       !goog.isDef(projections[code])) {
     var def = proj4.defs(code);
-    if (goog.isDef(def)) {
+    if (def !== undefined) {
       if (goog.isDef(def.axis) && !goog.isDef(options.axisOrientation)) {
         this.axisOrientation_ = def.axis;
       }
@@ -165,7 +165,7 @@ ol.proj.Projection = function(options) {
       var currentCode, currentDef, currentProj, proj4Transform;
       for (currentCode in projections) {
         currentDef = proj4.defs(currentCode);
-        if (goog.isDef(currentDef)) {
+        if (currentDef !== undefined) {
           currentProj = ol.proj.get(currentCode);
           if (currentDef === def) {
             ol.proj.addEquivalentProjections([currentProj, this]);
@@ -361,7 +361,7 @@ ol.proj.Projection.prototype.getPointResolution_ = function(resolution, point) {
         vertices.slice(4, 6), vertices.slice(6, 8));
     var pointResolution = (width + height) / 2;
     var metersPerUnit = this.getMetersPerUnit();
-    if (goog.isDef(metersPerUnit)) {
+    if (metersPerUnit !== undefined) {
       pointResolution /= metersPerUnit;
     }
     return pointResolution;
@@ -761,7 +761,7 @@ ol.proj.identityTransform = function(input, opt_output, opt_dimension) {
  */
 ol.proj.cloneTransform = function(input, opt_output, opt_dimension) {
   var output;
-  if (goog.isDef(opt_output)) {
+  if (opt_output !== undefined) {
     for (var i = 0, ii = input.length; i < ii; ++i) {
       opt_output[i] = input[i];
     }

src/ol/render/canvas/canvasimmediate.js

@@ -417,7 +417,7 @@ ol.render.canvas.Immediate.prototype.drawRings_ =
 ol.render.canvas.Immediate.prototype.drawAsync = function(zIndex, callback) {
   var zIndexKey = zIndex.toString();
   var callbacks = this.callbacksByZIndex_[zIndexKey];
-  if (goog.isDef(callbacks)) {
+  if (callbacks !== undefined) {
     callbacks.push(callback);
   } else {
     this.callbacksByZIndex_[zIndexKey] = [callback];

src/ol/render/canvas/canvasreplay.js

@@ -406,7 +406,7 @@ ol.render.canvas.Replay.prototype.replay_ = function(
         ++i;
         break;
       case ol.render.canvas.Instruction.END_GEOMETRY:
-        if (goog.isDef(featureCallback)) {
+        if (featureCallback !== undefined) {
           feature = /** @type {ol.Feature} */ (instruction[1]);
           var result = featureCallback(feature);
           if (result) {
@@ -1220,7 +1220,7 @@ ol.render.canvas.PolygonReplay.prototype.drawCircleGeometry =
   if (!goog.isDef(fillStyle) && !goog.isDef(strokeStyle)) {
     return;
   }
-  if (goog.isDef(strokeStyle)) {
+  if (strokeStyle !== undefined) {
     goog.asserts.assert(goog.isDef(state.lineWidth),
         'state.lineWidth should be defined');
   }
@@ -1273,7 +1273,7 @@ ol.render.canvas.PolygonReplay.prototype.drawPolygonGeometry =
   if (!goog.isDef(fillStyle) && !goog.isDef(strokeStyle)) {
     return;
   }
-  if (goog.isDef(strokeStyle)) {
+  if (strokeStyle !== undefined) {
     goog.asserts.assert(goog.isDef(state.lineWidth),
         'state.lineWidth should be defined');
   }
@@ -1309,7 +1309,7 @@ ol.render.canvas.PolygonReplay.prototype.drawMultiPolygonGeometry =
   if (!goog.isDef(fillStyle) && !goog.isDef(strokeStyle)) {
     return;
   }
-  if (goog.isDef(strokeStyle)) {
+  if (strokeStyle !== undefined) {
     goog.asserts.assert(goog.isDef(state.lineWidth),
         'state.lineWidth should be defined');
   }
@@ -1446,7 +1446,7 @@ ol.render.canvas.PolygonReplay.prototype.setFillStrokeStyles_ = function() {
         [ol.render.canvas.Instruction.SET_FILL_STYLE, fillStyle]);
     state.currentFillStyle = state.fillStyle;
   }
-  if (goog.isDef(strokeStyle)) {
+  if (strokeStyle !== undefined) {
     goog.asserts.assert(goog.isDef(lineCap), 'lineCap should be defined');
     goog.asserts.assert(!goog.isNull(lineDash), 'lineDash should not be null');
     goog.asserts.assert(goog.isDef(lineJoin), 'lineJoin should be defined');
@@ -1984,7 +1984,7 @@ ol.render.canvas.ReplayGroup.prototype.replay = function(
     replays = this.replaysByZIndex_[zs[i].toString()];
     for (j = 0, jj = ol.render.REPLAY_ORDER.length; j < jj; ++j) {
       replay = replays[ol.render.REPLAY_ORDER[j]];
-      if (goog.isDef(replay)) {
+      if (replay !== undefined) {
         replay.replay(context, pixelRatio, transform, viewRotation,
             skippedFeaturesHash);
       }
@@ -2020,7 +2020,7 @@ ol.render.canvas.ReplayGroup.prototype.replayHitDetection_ = function(
     replays = this.replaysByZIndex_[zs[i].toString()];
     for (j = ol.render.REPLAY_ORDER.length - 1; j >= 0; --j) {
       replay = replays[ol.render.REPLAY_ORDER[j]];
-      if (goog.isDef(replay)) {
+      if (replay !== undefined) {
         result = replay.replayHitDetection(context, transform, viewRotation,
             skippedFeaturesHash, featureCallback, opt_hitExtent);
         if (result) {

src/ol/render/webgl/webglimmediate.js

@@ -103,7 +103,7 @@ ol.render.webgl.Immediate.prototype.flush = function() {
 ol.render.webgl.Immediate.prototype.drawAsync = function(zIndex, callback) {
   var zIndexKey = zIndex.toString();
   var callbacks = this.callbacksByZIndex_[zIndexKey];
-  if (goog.isDef(callbacks)) {
+  if (callbacks !== undefined) {
     callbacks.push(callback);
   } else {
     this.callbacksByZIndex_[zIndexKey] = [callback];

src/ol/render/webgl/webglreplay.js

@@ -1078,7 +1078,7 @@ ol.render.webgl.ReplayGroup.prototype.replay = function(context,
   var i, ii, replay, result;
   for (i = 0, ii = ol.render.REPLAY_ORDER.length; i < ii; ++i) {
     replay = this.replays_[ol.render.REPLAY_ORDER[i]];
-    if (goog.isDef(replay)) {
+    if (replay !== undefined) {
       replay.replay(context,
           center, resolution, rotation, size, pixelRatio,
           opacity, brightness, contrast, hue, saturation, skippedFeaturesHash,
@@ -1117,7 +1117,7 @@ ol.render.webgl.ReplayGroup.prototype.replayHitDetection_ = function(context,
   var i, replay, result;
   for (i = ol.render.REPLAY_ORDER.length - 1; i >= 0; --i) {
     replay = this.replays_[ol.render.REPLAY_ORDER[i]];
-    if (goog.isDef(replay)) {
+    if (replay !== undefined) {
       result = replay.replay(context,
           center, resolution, rotation, size, pixelRatio,
           opacity, brightness, contrast, hue, saturation,

src/ol/renderer/layerrenderer.js

@@ -221,7 +221,7 @@ ol.renderer.Layer.prototype.updateAttributions =
  */
 ol.renderer.Layer.prototype.updateLogos = function(frameState, source) {
   var logo = source.getLogo();
-  if (goog.isDef(logo)) {
+  if (logo !== undefined) {
     if (goog.isString(logo)) {
       frameState.logos[logo] = '';
     } else if (goog.isObject(logo)) {
@@ -319,7 +319,7 @@ ol.renderer.Layer.prototype.manageTilePyramid = function(
                 tileGrid.getTileCoordCenter(tile.tileCoord), tileResolution]);
             }
           }
-          if (goog.isDef(opt_tileCallback)) {
+          if (opt_tileCallback !== undefined) {
             opt_tileCallback.call(opt_this, tile);
           }
         } else {

src/ol/resolutionconstraint.js

@@ -25,7 +25,7 @@ ol.ResolutionConstraint.createSnapToResolutions =
        * @return {number|undefined} Resolution.
        */
       function(resolution, delta, direction) {
-        if (goog.isDef(resolution)) {
+        if (resolution !== undefined) {
           var z =
               ol.array.linearFindNearest(resolutions, resolution, direction);
           z = goog.math.clamp(z + delta, 0, resolutions.length - 1);
@@ -53,7 +53,7 @@ ol.ResolutionConstraint.createSnapToPower =
        * @return {number|undefined} Resolution.
        */
       function(resolution, delta, direction) {
-        if (goog.isDef(resolution)) {
+        if (resolution !== undefined) {
           var offset;
           if (direction > 0) {
             offset = 0;
@@ -65,7 +65,7 @@ ol.ResolutionConstraint.createSnapToPower =
           var oldLevel = Math.floor(
               Math.log(maxResolution / resolution) / Math.log(power) + offset);
           var newLevel = Math.max(oldLevel + delta, 0);
-          if (goog.isDef(opt_maxLevel)) {
+          if (opt_maxLevel !== undefined) {
             newLevel = Math.min(newLevel, opt_maxLevel);
           }
           return maxResolution / Math.pow(power, newLevel);

src/ol/rotationconstraint.js

@@ -16,7 +16,7 @@ ol.RotationConstraintType;
  * @return {number|undefined} Rotation.
  */
 ol.RotationConstraint.disable = function(rotation, delta) {
-  if (goog.isDef(rotation)) {
+  if (rotation !== undefined) {
     return 0;
   } else {
     return undefined;
@@ -30,7 +30,7 @@ ol.RotationConstraint.disable = function(rotation, delta) {
  * @return {number|undefined} Rotation.
  */
 ol.RotationConstraint.none = function(rotation, delta) {
-  if (goog.isDef(rotation)) {
+  if (rotation !== undefined) {
     return rotation + delta;
   } else {
     return undefined;
@@ -51,7 +51,7 @@ ol.RotationConstraint.createSnapToN = function(n) {
        * @return {number|undefined} Rotation.
        */
       function(rotation, delta) {
-        if (goog.isDef(rotation)) {
+        if (rotation !== undefined) {
           rotation = Math.floor((rotation + delta) / theta + 0.5) * theta;
           return rotation;
         } else {
@@ -74,7 +74,7 @@ ol.RotationConstraint.createSnapToZero = function(opt_tolerance) {
        * @return {number|undefined} Rotation.
        */
       function(rotation, delta) {
-        if (goog.isDef(rotation)) {
+        if (rotation !== undefined) {
           if (Math.abs(rotation + delta) <= tolerance) {
             return 0;
           } else {

src/ol/source/imagemapguidesource.js

@@ -149,7 +149,7 @@ ol.source.ImageMapGuide.prototype.getImage =
   var size = [width * pixelRatio, height * pixelRatio];
 
   var imageUrl = this.imageUrlFunction_(extent, size, projection);
-  if (goog.isDef(imageUrl)) {
+  if (imageUrl !== undefined) {
     image = new ol.Image(extent, resolution, pixelRatio,
         this.getAttributions(), imageUrl, this.crossOrigin_,
         this.imageLoadFunction_);

src/ol/source/tilevectorsource.js

@@ -129,7 +129,7 @@ ol.source.TileVector.prototype.forEachFeatureAtCoordinateAndResolution =
 
   var tileKey = this.getTileKeyZXY_(tileCoord[0], tileCoord[1], tileCoord[2]);
   var features = tiles[tileKey];
-  if (goog.isDef(features)) {
+  if (features !== undefined) {
     var i, ii;
     for (i = 0, ii = features.length; i < ii; ++i) {
       var feature = features[i];
@@ -168,7 +168,7 @@ ol.source.TileVector.prototype.forEachFeatureInExtentAtResolution =
     for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
       var tileKey = this.getTileKeyZXY_(z, x, y);
       var features = tiles[tileKey];
-      if (goog.isDef(features)) {
+      if (features !== undefined) {
         var i, ii;
         for (i = 0, ii = features.length; i < ii; ++i) {
           var result = f.call(opt_this, features[i]);
@@ -305,7 +305,7 @@ ol.source.TileVector.prototype.loadFeatures =
             tileCoord, projection);
         var url = goog.isNull(urlTileCoord) ? undefined :
             tileUrlFunction(urlTileCoord, 1, projection);
-        if (goog.isDef(url)) {
+        if (url !== undefined) {
           tiles[tileKey] = [];
           var tileSuccess = goog.partial(success, tileKey);
           if (!goog.isNull(this.tileLoadFunction_)) {

src/ol/source/vectorsource.js

@@ -164,10 +164,10 @@ ol.source.Vector = function(opt_options) {
   if (!useSpatialIndex && !goog.isDef(collection)) {
     collection = new ol.Collection(features);
   }
-  if (goog.isDef(features)) {
+  if (features !== undefined) {
     this.addFeaturesInternal(features);
   }
-  if (goog.isDef(collection)) {
+  if (collection !== undefined) {
     this.bindFeaturesCollection_(collection);
   }
 
@@ -246,7 +246,7 @@ ol.source.Vector.prototype.setupChangeEvents_ = function(featureKey, feature) {
 ol.source.Vector.prototype.addToIndex_ = function(featureKey, feature) {
   var valid = true;
   var id = feature.getId();
-  if (goog.isDef(id)) {
+  if (id !== undefined) {
     if (!(id.toString() in this.idIndex_)) {
       this.idIndex_[id.toString()] = feature;
     } else {
@@ -726,7 +726,7 @@ ol.source.Vector.prototype.handleFeatureChange_ = function(event) {
   }
   var id = feature.getId();
   var removed;
-  if (goog.isDef(id)) {
+  if (id !== undefined) {
     var sid = id.toString();
     if (featureKey in this.undefIdIndex_) {
       delete this.undefIdIndex_[featureKey];
@@ -827,7 +827,7 @@ ol.source.Vector.prototype.removeFeatureInternal = function(feature) {
       goog.events.unlistenByKey);
   delete this.featureChangeKeys_[featureKey];
   var id = feature.getId();
-  if (goog.isDef(id)) {
+  if (id !== undefined) {
     delete this.idIndex_[id.toString()];
   } else {
     delete this.undefIdIndex_[featureKey];

src/ol/source/wmtssource.js

@@ -404,7 +404,7 @@ ol.source.WMTS.optionsFromCapabilities = function(wmtsCap, config) {
     goog.array.forEach(l['Dimension'], function(elt, index, array) {
       var key = elt['Identifier'];
       var value = elt['default'];
-      if (goog.isDef(value)) {
+      if (value !== undefined) {
         goog.asserts.assert(goog.array.contains(elt['values'], value),
             'default value contained in values');
       } else {
@@ -432,7 +432,7 @@ ol.source.WMTS.optionsFromCapabilities = function(wmtsCap, config) {
 
   var wgs84BoundingBox = l['WGS84BoundingBox'];
   var extent, wrapX;
-  if (goog.isDef(wgs84BoundingBox)) {
+  if (wgs84BoundingBox !== undefined) {
     var wgs84ProjectionExtent = ol.proj.get('EPSG:4326').getExtent();
     wrapX = (wgs84BoundingBox[0] == wgs84ProjectionExtent[0] &&
         wgs84BoundingBox[2] == wgs84ProjectionExtent[2]);

src/ol/style/style.js

@@ -172,7 +172,7 @@ ol.style.Style.prototype.setGeometry = function(geometry) {
     };
   } else if (goog.isNull(geometry)) {
     this.geometryFunction_ = ol.style.defaultGeometryFunction;
-  } else if (goog.isDef(geometry)) {
+  } else if (geometry !== undefined) {
     goog.asserts.assertInstanceof(geometry, ol.geom.Geometry,
         'geometry must be an ol.geom.Geometry instance');
     this.geometryFunction_ = function() {

src/ol/tilecoord.js

@@ -50,7 +50,7 @@ ol.tilecoord.createFromString = function(str) {
  * @return {ol.TileCoord} Tile coordinate.
  */
 ol.tilecoord.createOrUpdate = function(z, x, y, opt_tileCoord) {
-  if (goog.isDef(opt_tileCoord)) {
+  if (opt_tileCoord !== undefined) {
     opt_tileCoord[0] = z;
     opt_tileCoord[1] = x;
     opt_tileCoord[2] = y;

src/ol/tilerange.js

@@ -79,7 +79,7 @@ ol.TileRange.boundingTileRange = function(var_args) {
  * @return {ol.TileRange} Tile range.
  */
 ol.TileRange.createOrUpdate = function(minX, maxX, minY, maxY, tileRange) {
-  if (goog.isDef(tileRange)) {
+  if (tileRange !== undefined) {
     tileRange.minX = minX;
     tileRange.maxX = maxX;
     tileRange.minY = minY;

src/ol/view.js

@@ -175,7 +175,7 @@ goog.inherits(ol.View, ol.Object);
 ol.View.prototype.calculateCenterRotate = function(rotation, anchor) {
   var center;
   var currentCenter = this.getCenter();
-  if (goog.isDef(currentCenter)) {
+  if (currentCenter !== undefined) {
     center = [currentCenter[0] - anchor[0], currentCenter[1] - anchor[1]];
     ol.coordinate.rotate(center, rotation - this.getRotation());
     ol.coordinate.add(center, anchor);
@@ -421,7 +421,7 @@ ol.View.prototype.getZoom = function() {
   var offset;
   var resolution = this.getResolution();
 
-  if (goog.isDef(resolution)) {
+  if (resolution !== undefined) {
     var res, z = 0;
     do {
       res = this.constrainResolution(this.maxResolution_, z);
@@ -564,7 +564,7 @@ ol.View.prototype.isDef = function() {
  * @api stable
  */
 ol.View.prototype.rotate = function(rotation, opt_anchor) {
-  if (goog.isDef(opt_anchor)) {
+  if (opt_anchor !== undefined) {
     var center = this.calculateCenterRotate(rotation, opt_anchor);
     this.setCenter(center);
   }
@@ -695,7 +695,7 @@ ol.View.createResolutionConstraint_ = function(options) {
 
     // user provided maxResolution takes precedence
     maxResolution = options.maxResolution;
-    if (goog.isDef(maxResolution)) {
+    if (maxResolution !== undefined) {
       minZoom = 0;
     } else {
       maxResolution = defaultMaxResolution / Math.pow(zoomFactor, minZoom);

src/ol/webgl/context.js

@@ -367,11 +367,11 @@ ol.webgl.Context.createTexture_ = function(gl, opt_wrapS, opt_wrapT) {
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
 
-  if (goog.isDef(opt_wrapS)) {
+  if (opt_wrapS !== undefined) {
     gl.texParameteri(
         goog.webgl.TEXTURE_2D, goog.webgl.TEXTURE_WRAP_S, opt_wrapS);
   }
-  if (goog.isDef(opt_wrapT)) {
+  if (opt_wrapT !== undefined) {
     gl.texParameteri(
         goog.webgl.TEXTURE_2D, goog.webgl.TEXTURE_WRAP_T, opt_wrapT);
   }

src/ol/xml.js

@@ -132,7 +132,7 @@ ol.xml.getLocalName_ = function(node) {
  */
 ol.xml.getLocalNameIE_ = function(node) {
   var localName = node.localName;
-  if (goog.isDef(localName)) {
+  if (localName !== undefined) {
     return localName;
   }
   var baseName = node.baseName;
@@ -227,7 +227,7 @@ ol.xml.getAttributeNS_ = function(node, namespaceURI, name) {
 ol.xml.getAttributeNSActiveX_ = function(node, namespaceURI, name) {
   var attributeValue = '';
   var attributeNode = ol.xml.getAttributeNodeNS(node, namespaceURI, name);
-  if (goog.isDef(attributeNode)) {
+  if (attributeNode !== undefined) {
     attributeValue = attributeNode.nodeValue;
   }
   return attributeValue;
@@ -363,7 +363,7 @@ ol.xml.makeArrayExtender = function(valueReader, opt_this) {
        */
       function(node, objectStack) {
         var value = valueReader.call(opt_this, node, objectStack);
-        if (goog.isDef(value)) {
+        if (value !== undefined) {
           goog.asserts.assert(goog.isArray(value),
               'valueReader function is expected to return an array of values');
           var array = /** @type {Array.<*>} */
@@ -393,7 +393,7 @@ ol.xml.makeArrayPusher = function(valueReader, opt_this) {
       function(node, objectStack) {
         var value = valueReader.call(goog.isDef(opt_this) ? opt_this : this,
             node, objectStack);
-        if (goog.isDef(value)) {
+        if (value !== undefined) {
           var array = objectStack[objectStack.length - 1];
           goog.asserts.assert(goog.isArray(array),
               'objectStack is supposed to be an array of arrays');
@@ -420,7 +420,7 @@ ol.xml.makeReplacer = function(valueReader, opt_this) {
       function(node, objectStack) {
         var value = valueReader.call(goog.isDef(opt_this) ? opt_this : this,
             node, objectStack);
-        if (goog.isDef(value)) {
+        if (value !== undefined) {
           objectStack[objectStack.length - 1] = value;
         }
       });
@@ -448,7 +448,7 @@ ol.xml.makeObjectPropertyPusher =
       function(node, objectStack) {
         var value = valueReader.call(goog.isDef(opt_this) ? opt_this : this,
             node, objectStack);
-        if (goog.isDef(value)) {
+        if (value !== undefined) {
           var object = /** @type {Object} */
               (objectStack[objectStack.length - 1]);
           var property = goog.isDef(opt_property) ?
@@ -482,7 +482,7 @@ ol.xml.makeObjectPropertySetter =
       function(node, objectStack) {
         var value = valueReader.call(goog.isDef(opt_this) ? opt_this : this,
             node, objectStack);
-        if (goog.isDef(value)) {
+        if (value !== undefined) {
           var object = /** @type {Object} */
               (objectStack[objectStack.length - 1]);
           var property = goog.isDef(opt_property) ?
@@ -658,9 +658,9 @@ ol.xml.parseNode = function(parsersNS, node, objectStack, opt_this) {
   var n;
   for (n = node.firstElementChild; !goog.isNull(n); n = n.nextElementSibling) {
     var parsers = parsersNS[n.namespaceURI];
-    if (goog.isDef(parsers)) {
+    if (parsers !== undefined) {
       var parser = parsers[n.localName];
-      if (goog.isDef(parser)) {
+      if (parser !== undefined) {
         parser.call(opt_this, n, objectStack);
       }
     }
@@ -715,10 +715,10 @@ ol.xml.serialize = function(
   var value, node;
   for (var i = 0; i < length; ++i) {
     value = values[i];
-    if (goog.isDef(value)) {
+    if (value !== undefined) {
       node = nodeFactory.call(opt_this, value, objectStack,
           goog.isDef(opt_keys) ? opt_keys[i] : undefined);
-      if (goog.isDef(node)) {
+      if (node !== undefined) {
         serializersNS[node.namespaceURI][node.localName]
             .call(opt_this, node, value, objectStack);
       }