[DevTools] Do not inherit ObjectPopoverHelper from PopoverHelper.

third_party/WebKit/Source/devtools/front_end/source_frame/UISourceCodeFrame.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:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 382 matching lines @@
   _getErrorAnchor(target, event) {
     var element = target.enclosingNodeOrSelfWithClass('text-editor-line-decoration-icon') ||
         target.enclosingNodeOrSelfWithClass('text-editor-line-decoration-wave');
     if (!element)
       return;
     this._errorWavePopoverAnchor = new AnchorBox(event.clientX, event.clientY, 1, 1);
     return element;
   }
 
   /**
-   * @param {!Element} anchor
+   * @param {!Element|!AnchorBox} anchor
    * @param {!UI.GlassPane} popover
    * @return {!Promise<boolean>}
    */
   _showErrorPopover(anchor, popover) {
-    var messageBucket = anchor.enclosingNodeOrSelfWithClass('text-editor-line-decoration')._messageBucket;
+    var element = /** @type {!Element} */ (anchor);
+    var messageBucket = element.enclosingNodeOrSelfWithClass('text-editor-line-decoration')._messageBucket;
     var messagesOutline = messageBucket.messagesDescription();
     popover.setContentAnchorBox(
-        anchor.enclosingNodeOrSelfWithClass('text-editor-line-decoration-icon') ? anchor.boxInWindow() :
-                                                                                  this._errorWavePopoverAnchor);
+        element.enclosingNodeOrSelfWithClass('text-editor-line-decoration-icon') ? element.boxInWindow() :
+                                                                                   this._errorWavePopoverAnchor);
     popover.contentElement.appendChild(messagesOutline);
     return Promise.resolve(true);
   }
 
   _updateBucketDecorations() {
     for (var bucket of this._rowMessageBuckets.values())
       bucket._updateDecoration();
   }
 
   /**
@@ skipping 259 matching lines @@
 
 /**
  * @param {!Workspace.UISourceCode.Message} a
  * @param {!Workspace.UISourceCode.Message} b
  * @return {number}
  */
 Workspace.UISourceCode.Message.messageLevelComparator = function(a, b) {
   return Workspace.UISourceCode.Message._messageLevelPriority[a.level()] -
       Workspace.UISourceCode.Message._messageLevelPriority[b.level()];
 };