Fixes a bug where touch device scripts were not cleared on exit of device mode in devtools.

Source/devtools/front_end/emulation/OverridesSupport.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 692 matching lines @@
                 for (var j = 0; j < recepients.length; ++j) {
                     if (!(touchEvents[i] in recepients[j]))
                         Object.defineProperty(recepients[j], touchEvents[i], { value: null, writable: true, configurable: true, enumerable: true });
                 }
             }
         }
 
         var symbol = WebInspector.OverridesSupport._touchEventsScriptIdSymbol;
 
         if (emulationEnabled && target[symbol] !== -1) {
+            if (typeof target[symbol] !== "undefined")
+                target.pageAgent().removeScriptToEvaluateOnLoad(target[symbol]);

[dgozman, 2015/08/25 18:02:09]

This is getting messy. Could you please rewrite this whole section to:
- always remove the old script;
- add the new one if necessary.

+
             target[symbol] = -1;
             target.pageAgent().addScriptToEvaluateOnLoad("(" + injectedFunction.toString() + ")()", scriptAddedCallback);
         } else {
             if (typeof target[symbol] !== "undefined") {
                 target.pageAgent().removeScriptToEvaluateOnLoad(target[symbol]);
                 delete target[symbol];
             }
         }
 
         /**
@@ skipping 95 matching lines @@
     },
 
     __proto__: WebInspector.Object.prototype
 }
 
 
 /**
  * @type {!WebInspector.OverridesSupport}
  */
 WebInspector.overridesSupport;