[DevTools] Remove Common.Event.target field.

third_party/WebKit/Source/devtools/front_end/bindings/CompilerScriptMapping.js

 /*
  * Copyright (C) 2012 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 165 matching lines @@
       return;
     if (this._sourceMapForScriptId.has(script.scriptId))
       return;
     this._processScript(script);
   }
 
   /**
    * @param {!Common.Event} event
    */
   _sourceMapURLAdded(event) {
-    var script = /** @type {!SDK.Script} */ (event.target);
+    var script = /** @type {!SDK.Script} */ (event.data);
     if (!script.sourceMapURL)
       return;
     this._processScript(script);
   }
 
   /**
    * @param {!SDK.Script} script
    */
   _processScript(script) {
     if (Bindings.blackboxManager.isBlackboxedURL(script.sourceURL, script.isContentScript()))
@@ skipping 178 matching lines @@
   }
 
   dispose() {
     Common.EventTarget.removeEventListeners(this._eventListeners);
     this._debuggerReset();
     this._stubProject.dispose();
   }
 };
 
 Bindings.CompilerScriptMapping._originSymbol = Symbol('origin');