[inspector] Store interger in context embedder data instead of a string.

src/inspector/debugger_script_externs.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** @typedef {{
         type: string,
         object: !Object,
         name: (string|undefined),
         startLocation: (!RawLocation|undefined),
         endLocation: (!RawLocation|undefined)
@@ skipping 14 matching lines @@
         scopeChain: !Array<!Scope>,
         functionLocation: (RawLocation|undefined),
         returnValue: (*|undefined)
     }} */
 var JavaScriptCallFrameDetails;
 
 /** @typedef {{
         sourceID: function():(number),
         line: function():number,
         column: function():number,
+        contextId: function():number,
         thisObject: !Object,
         evaluate: function(string):*,
         restart: function():undefined,
         setVariableValue: function(number, string, *):undefined,
         isAtReturn: boolean,
         details: function():!JavaScriptCallFrameDetails
     }} */
 var JavaScriptCallFrame;
 
 /**
@@ skipping 437 matching lines @@
 ScopeMirror.prototype.setVariableValue = function(name, newValue) {}
 
 /**
  * @interface
  * @extends {Mirror}
  */
 function ContextMirror() {}
 
 /** @return {string|undefined} */
 ContextMirror.prototype.data = function() {}