DevTools: make debugger's rawLocationToUILocation return nullable type

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 844 matching lines @@
    */
   _prepareScopeVariables(callFrame, properties, internalProperties) {
     if (!properties || !properties.length || properties.length > 500 || !this.isShowing()) {
       this._clearValueWidgets();
       return;
     }
 
     var functionUILocation = Bindings.debuggerWorkspaceBinding.rawLocationToUILocation(
         /** @type {!SDK.DebuggerModel.Location} */ (callFrame.functionLocation()));
     var executionUILocation = Bindings.debuggerWorkspaceBinding.rawLocationToUILocation(callFrame.location());
-    if (functionUILocation.uiSourceCode !== this._debuggerSourceCode ||
+    if (!functionUILocation || !executionUILocation || functionUILocation.uiSourceCode !== this._debuggerSourceCode ||
         executionUILocation.uiSourceCode !== this._debuggerSourceCode) {
       this._clearValueWidgets();
       return;
     }
 
     var fromLine = functionUILocation.lineNumber;
     var fromColumn = functionUILocation.columnNumber;
     var toLine = executionUILocation.lineNumber;
 
     // Make sure we have a chance to update all existing widgets.
@@ skipping 803 matching lines @@
       return;
     this.bookmark.clear();
     this.bookmark = null;
   }
 };
 
 Sources.JavaScriptSourceFrame.BreakpointDecoration.bookmarkSymbol = Symbol('bookmark');
 Sources.JavaScriptSourceFrame.BreakpointDecoration._elementSymbolForTest = Symbol('element');
 
 Sources.JavaScriptSourceFrame.continueToLocationDecorationSymbol = Symbol('bookmark');