[DevTools] clean breakpoints and decorations onUISourceCodeContentChanged

third_party/WebKit/Source/devtools/front_end/sources/JavaScriptSourceFrame.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 167 matching lines @@
    */
   willHide() {
     super.willHide();
     this._popoverHelper.hidePopover();
   }
 
   /**
    * @override
    */
   onUISourceCodeContentChanged() {
-    for (var decoration of this._breakpointDecorations)
-      decoration.breakpoint.remove();
+    for (var decoration of this._breakpointDecorations) {
+      if (decoration.breakpoint)
+        decoration.breakpoint.remove();
+    }
     super.onUISourceCodeContentChanged();
   }
 
   /**
    * @override
    */
   onTextChanged(oldRange, newRange) {
     this._scriptsPanel.updateLastModificationTime();
     super.onTextChanged(oldRange, newRange);
     if (this._compiler)
@@ skipping 1121 matching lines @@
   hide() {
     if (!this.bookmark)
       return;
     this.bookmark.clear();
     this.bookmark = null;
   }
 };
 
 Sources.JavaScriptSourceFrame.BreakpointDecoration.bookmarkSymbol = Symbol('bookmark');
 Sources.JavaScriptSourceFrame.BreakpointDecoration._elementSymbolForTest = Symbol('element');