Merge pull request #2691 from fredj/will-change

Add will-change CSS properties

css/ol.css

@@ -21,7 +21,12 @@
   font-size: 10px;
   text-align: center;
   margin: 1px;
+  will-change: contents, width;
 }
+.ol-overlay-container {
+  will-change: left,right,top,bottom;
+}
+
 .ol-unsupported {
   display: none;
 }
@@ -101,6 +106,7 @@
   display: block;
   font-weight: normal;
   font-size: 1.2em;
+  will-change: transform;
 }
 .ol-touch .ol-control button {
   font-size: 1.5em;

src/ol/overlay.js

@@ -90,7 +90,9 @@ ol.Overlay = function(options) {
    * @private
    * @type {Element}
    */
-  this.element_ = goog.dom.createElement(goog.dom.TagName.DIV);
+  this.element_ = goog.dom.createDom(goog.dom.TagName.DIV, {
+    'class': 'ol-overlay-container'
+  });
   this.element_.style.position = 'absolute';
 
   /**