DevTools: use target-based model accessors only.

Source/devtools/front_end/sdk/CSSStyleModel.js

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 674 matching lines @@
         this[propertyIndex] = name;
         this._livePropertyMap[name] = property;
         ++propertyIndex;
     }
     this.length = propertyIndex;
     if ("cssText" in payload)
         this.cssText = payload.cssText;
 }
 
 /**
+ * @param {!WebInspector.Target} target
  * @return {!WebInspector.CSSStyleDeclaration}
  */
-WebInspector.CSSStyleDeclaration.createDummyStyle = function()
+WebInspector.CSSStyleDeclaration.createDummyStyle = function(target)
 {
     var dummyPayload = {
         shorthandEntries: [],
         cssProperties: []
     };
-    return new WebInspector.CSSStyleDeclaration(WebInspector.cssModel, dummyPayload);
+    return new WebInspector.CSSStyleDeclaration(target.cssModel, dummyPayload);
 }
 
 /**
  * @param {!Array.<!CSSAgent.ShorthandEntry>} shorthandEntries
  * @return {!Object}
  */
 WebInspector.CSSStyleDeclaration.buildShorthandValueMap = function(shorthandEntries)
 {
     var result = {};
     for (var i = 0; i < shorthandEntries.length; ++i)
@@ skipping 1097 matching lines @@
             // The loader has been reset.
             if (!callbacks)
                 return;
 
             delete this._nodeIdToCallbackData[nodeId];
             for (var i = 0; i < callbacks.length; ++i)
                 callbacks[i](computedStyle);
         }
     }
 }
-
-/**
- * @type {!WebInspector.CSSStyleModel}
- */
-WebInspector.cssModel;