Fix coding style

Use `goog.isDef(x) ? x : {}` instead of `x || {}`

src/ol/control/scalelinecontrol.js

@@ -55,7 +55,7 @@ ol.control.ScaleLineUnits = {
  */
 ol.control.ScaleLine = function(opt_options) {
 
-  var options = opt_options || {};
+  var options = goog.isDef(opt_options) ? opt_options : {};
 
   var className = goog.isDef(options.className) ?
       options.className : 'ol-scale-line';

src/ol/source/wmtssource.js

@@ -42,7 +42,7 @@ ol.source.WMTS = function(options) {
    * @private
    * @type {Object}
    */
-  this.dimensions_ = options.dimensions || {};
+  this.dimensions_ = goog.isDef(options.dimensions) ? options.dimensions : {};
 
   /**
    * @private

src/ol/view2d.js

@@ -94,7 +94,7 @@ ol.View2DProperty = {
  */
 ol.View2D = function(opt_options) {
   goog.base(this);
-  var options = opt_options || {};
+  var options = goog.isDef(opt_options) ? opt_options : {};
 
   /**
    * @type {Object.<string, *>}