DevTools: make debugger's rawLocationToUILocation return nullable type

third_party/WebKit/Source/devtools/front_end/bindings/DefaultScriptMapping.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:
  *
  *     * 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 48 matching lines @@
    * @param {!SDK.Target} target
    * @return {string}
    */
   static projectIdForTarget(target) {
     return 'debugger:' + target.id();
   }
 
   /**
    * @override
    * @param {!SDK.DebuggerModel.Location} rawLocation
-   * @return {!Workspace.UILocation}
+   * @return {?Workspace.UILocation}
    */
   rawLocationToUILocation(rawLocation) {
-    var debuggerModelLocation = /** @type {!SDK.DebuggerModel.Location} */ (rawLocation);
-    var script = debuggerModelLocation.script();
+    var script = rawLocation.script();
+    if (!script)
+      return null;
     var uiSourceCode = script[Bindings.DefaultScriptMapping._uiSourceCodeSymbol];
-    var lineNumber = debuggerModelLocation.lineNumber - (script.isInlineScriptWithSourceURL() ? script.lineOffset : 0);
-    var columnNumber = debuggerModelLocation.columnNumber || 0;
+    var lineNumber = rawLocation.lineNumber - (script.isInlineScriptWithSourceURL() ? script.lineOffset : 0);
+    var columnNumber = rawLocation.columnNumber || 0;
     if (script.isInlineScriptWithSourceURL() && !lineNumber && columnNumber)
       columnNumber -= script.columnOffset;
     return uiSourceCode.uiLocation(lineNumber, columnNumber);
   }
 
   /**
    * @override
    * @param {!Workspace.UISourceCode} uiSourceCode
    * @param {number} lineNumber
    * @param {number} columnNumber
@@ skipping 42 matching lines @@
 
   dispose() {
     Common.EventTarget.removeEventListeners(this._eventListeners);
     this._debuggerReset();
     this._project.dispose();
   }
 };
 
 Bindings.DefaultScriptMapping._scriptSymbol = Symbol('symbol');
 Bindings.DefaultScriptMapping._uiSourceCodeSymbol = Symbol('uiSourceCodeSymbol');