Properly cache the css transform support result

src/ol/dom/dom.js

@@ -26,15 +26,15 @@ ol.dom.BrowserFeature = {
  * http://caniuse.com/#feat=transforms2d
  * @return {boolean}
  */
-ol.dom.canUseCssTransform = function() {
-  goog.asserts.assert(!goog.isNull(document.body));
+ol.dom.canUseCssTransform = (function() {
   var canUseCssTransform;
+  return function() {
     if (!goog.isDef(canUseCssTransform)) {
-    canUseCssTransform = (function() {
+      goog.asserts.assert(!goog.isNull(document.body));
       if (!goog.global.getComputedStyle) {
         // this browser is ancient
-        return false;
-      }
+        canUseCssTransform = false;
+      } else {
         var el = goog.dom.createElement(goog.dom.TagName.P),
             has2d,
             transforms = {
@@ -54,12 +54,13 @@ ol.dom.canUseCssTransform = function() {
         }
         goog.dom.removeNode(el);
 
-      return (goog.isDefAndNotNull(has2d) && has2d.length > 0 &&
+        canUseCssTransform = (goog.isDefAndNotNull(has2d) && has2d.length > 0 &&
             has2d !== 'none');
-    }());
+      }
     }
     return canUseCssTransform;
-};
+  };
+}());
 
 
 /**
@@ -68,15 +69,15 @@ ol.dom.canUseCssTransform = function() {
  * http://caniuse.com/#feat=transforms3d
  * @return {boolean}
  */
-ol.dom.canUseCssTransform3D = function() {
-  goog.asserts.assert(!goog.isNull(document.body));
+ol.dom.canUseCssTransform3D = (function() {
   var canUseCssTransform3D;
+  return function() {
     if (!goog.isDef(canUseCssTransform3D)) {
-    canUseCssTransform3D = (function() {
+      goog.asserts.assert(!goog.isNull(document.body));
       if (!goog.global.getComputedStyle) {
         // this browser is ancient
-        return false;
-      }
+        canUseCssTransform3D = false;
+      } else {
         var el = goog.dom.createElement(goog.dom.TagName.P),
             has3d,
             transforms = {
@@ -96,12 +97,13 @@ ol.dom.canUseCssTransform3D = function() {
         }
         goog.dom.removeNode(el);
 
-      return (goog.isDefAndNotNull(has3d) && has3d.length > 0 &&
-          has3d !== 'none');
-    }());
+        canUseCssTransform3D = (goog.isDefAndNotNull(has3d) &&
+            has3d.length > 0 && has3d !== 'none');
+      }
     }
     return canUseCssTransform3D;
-};
+  };
+}());
 
 
 /**