DevTools: NOOP if outline dialog is not available for the content type

Source/devtools/front_end/sources/SourcesView.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @implements {WebInspector.TabbedEditorContainerDelegate}
  * @implements {WebInspector.Searchable}
  * @implements {WebInspector.Replaceable}
  * @extends {WebInspector.VBox}
@@ skipping 593 matching lines @@
             return false;
 
         switch (uiSourceCode.contentType()) {
         case WebInspector.resourceTypes.Document:
         case WebInspector.resourceTypes.Script:
             WebInspector.JavaScriptOutlineDialog.show(this, uiSourceCode, this.showSourceLocation.bind(this, uiSourceCode));
             return true;
         case WebInspector.resourceTypes.Stylesheet:
             WebInspector.StyleSheetOutlineDialog.show(this, uiSourceCode, this.showSourceLocation.bind(this, uiSourceCode));
             return true;
+        default:
+            // We don't want default browser shortcut to be executed, so pretend to handle this event.
+            return true;
         }
-        return false;
     },
 
     /**
      * @param {string=} query
      */
     showOpenResourceDialog: function(query)
     {
         var uiSourceCodes = this._editorContainer.historyUISourceCodes();
         /** @type {!Map.<!WebInspector.UISourceCode, number>} */
         var defaultScores = new Map();
@@ skipping 144 matching lines @@
         var currentUISourceCode = sourcesView.currentUISourceCode();
         if (!currentUISourceCode)
             return true;
         var nextUISourceCode = WebInspector.SourcesView.SwitchFileActionDelegate._nextFile(currentUISourceCode);
         if (!nextUISourceCode)
             return true;
         sourcesView.showSourceLocation(nextUISourceCode);
         return true;
     }
 }