DevTools: Decouple shortcuts from actions, introduce shortcut contexts

Source/devtools/front_end/InspectorView.js

 /*
  * Copyright (C) 2011 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 178 matching lines @@
      * @param {boolean} available
      */
     setDrawerEditorAvailable: function(available)
     {
         this._drawer.setDrawerEditorAvailable(available);
     },
 
     _tabSelected: function()
     {
         var panelName = this._tabbedPane.selectedTabId;
+        if (!panelName)
+            return;
         var panel = this._panelDescriptors[this._tabbedPane.selectedTabId].panel();
         this._tabbedPane.changeTabView(panelName, panel);
 
         this._currentPanel = panel;
         this._lastActivePanelSetting.set(panel.name);
         this._pushToHistory(panel.name);
         WebInspector.userMetrics.panelShown(panel.name);
         panel.focus();
     },
 
@@ skipping 43 matching lines @@
     /**
      * @param {string} id
      * @param {boolean=} immediate
      */
     showViewInDrawer: function(id, immediate)
     {
         this._drawer.showView(id, immediate);
     },
 
     /**
-     * @return {string}
+     * @return {?string}
      */
     selectedViewInDrawer: function()
     {
         return this._drawer.selectedViewId();
     },
 
     closeDrawer: function()
     {
         this._drawer.closeDrawer();
     },
@@ skipping 233 matching lines @@
             window.addEventListener("scroll", this._onScrollBound, false);
         else
             window.removeEventListener("scroll", this._onScrollBound, false);
 
         WebInspector.VBox.prototype.doResize.call(this);
         this._onScroll();
     },
 
     __proto__: WebInspector.VBox.prototype
 };