DevTools: represent ComputedStyle with simple Map

Source/devtools/front_end/elements/StylesSidebarPane.js

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 2047 matching lines @@
         if (!this._styleRule.editable()) {
             var swatch = WebInspector.ColorSwatch.create();
             swatch.setColorText(text);
             return swatch;
         }
 
         var stylesPopoverHelper = this._parentPane._stylesPopoverHelper;
         var swatchIcon = new WebInspector.ColorSwatchPopoverIcon(this, stylesPopoverHelper, text);
 
         /**
-         * @param {?WebInspector.CSSStyleDeclaration} styles
+         * @param {?Map.<string, string>} styles
          */
         function computedCallback(styles)
         {
             if (!styles)
                 return;
-            var bgColorText = styles.getPropertyValue("background-color") || "";
+            var bgColorText = styles.get("background-color") || "";
             var bgColor = WebInspector.Color.parse(bgColorText);
             // TODO(aboxhall): for background color with alpha, compute the actual
             // visible background color (blended with content underneath).
             if (bgColor && !bgColor.hasAlpha())
                 swatchIcon.setContrastColor(bgColor);
         }
 
         if (this.property.name === "color" && this._parentPane.cssModel() && this.node()) {
             var cssModel = this._parentPane.cssModel();
             cssModel.computedStylePromise(this.node().id).then(computedCallback);
@@ skipping 1165 matching lines @@
 
     /**
      * @override
      * @return {?WebInspector.ToolbarItem}
      */
     item: function()
     {
         return this._button;
     }
 }