DevTools: rely on response's "Content-Type" header to refine resource type

Source/devtools/front_end/sdk/Resource.js

 /*
  * Copyright (C) 2007, 2008 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 247 matching lines @@
     {
         return this._url;
     },
 
     /**
      * @override
      * @return {!WebInspector.ResourceType}
      */
     contentType: function()
     {
+        if (this.resourceType() === WebInspector.resourceTypes.Document && this.mimeType.indexOf("javascript") !== -1)
+            return WebInspector.resourceTypes.Script;
         return this.resourceType();
     },
 
     /**
      * @override
      * @param {function(?string)} callback
      */
     requestContent: function(callback)
     {
         if (typeof this._content !== "undefined") {
             callback(this._content);
             return;
         }
 
         this._pendingContentCallbacks.push(callback);
         if (!this._request || this._request.finished)
             this._innerRequestContent();
     },
 
     /**
      * @return {string}
      */
     canonicalMimeType: function()
     {
-        return this.resourceType().canonicalMimeType() || this.mimeType;
+        return this.contentType().canonicalMimeType() || this.mimeType;
     },
 
     /**
      * @override
      * @param {string} query
      * @param {boolean} caseSensitive
      * @param {boolean} isRegex
      * @param {function(!Array.<!WebInspector.ContentProvider.SearchMatch>)} callback
      */
     searchInContent: function(query, caseSensitive, isRegex, callback)
@@ skipping 111 matching lines @@
         if (this._type.isTextType())
             return true;
         if (this._type === WebInspector.resourceTypes.Other)
             return !!this._content && !this._contentEncoded;
         return false;
     },
 
     __proto__: WebInspector.SDKObject.prototype
 }