DevTools: Process correctly a disconnection during target initialization

Source/devtools/front_end/main/Main.js

Index: Source/devtools/front_end/main/Main.js
diff --git a/Source/devtools/front_end/main/Main.js b/Source/devtools/front_end/main/Main.js
index 040c995cc7b2fb34afa8f95b46c2ba88513dcb38..12d9778651f7ed09fe74fa1aad8883af6bc3f63c 100644
--- a/Source/devtools/front_end/main/Main.js
+++ b/Source/devtools/front_end/main/Main.js
@@ -318,12 +318,13 @@ WebInspector.Main.prototype = {
     },
 
     /**
-     * @param {!WebInspector.Target} mainTarget
+     * @param {?WebInspector.Target} target
      */
-    _mainTargetCreated: function(mainTarget)
+    _mainTargetCreated: function(target)
     {
         console.timeStamp("Main._mainTargetCreated");
 
+        var mainTarget = /** @type {!WebInspector.Target} */(target);
         this._registerShortcuts();
 
         WebInspector.workerTargetManager = new WebInspector.WorkerTargetManager(mainTarget, WebInspector.targetManager);