Revert of Make profiling lock global rather than per Target

Source/devtools/front_end/common/Object.js

 /*
  * Copyright (C) 2008 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 127 matching lines @@
      */
     consume: function(preventDefault)
     {
         this.stopPropagation();
         if (preventDefault)
             this.preventDefault();
     }
 }
 
 /**
+ * @constructor
+ * @extends {WebInspector.Object}
+ */
+WebInspector.Lock = function()
+{
+    this._count = 0; // Reentrant.
+}
+
+/**
+ * @enum {string}
+ */
+WebInspector.Lock.Events = {
+    StateChanged: "StateChanged"
+}
+
+WebInspector.Lock.prototype = {
+    /**
+     * @return {boolean}
+     */
+    isAcquired: function()
+    {
+        return !!this._count;
+    },
+
+    acquire: function()
+    {
+        if (++this._count === 1)
+            this.dispatchEventToListeners(WebInspector.Lock.Events.StateChanged);
+    },
+
+    release: function()
+    {
+        --this._count;
+        if (this._count < 0) {
+            console.error("WebInspector.Lock acquire/release calls are unbalanced " + new Error().stack);
+            return;
+        }
+        if (!this._count)
+            this.dispatchEventToListeners(WebInspector.Lock.Events.StateChanged);
+    },
+
+    __proto__: WebInspector.Object.prototype
+}
+
+/**
  * @interface
  */
 WebInspector.EventTarget = function()
 {
 }
 
 WebInspector.EventTarget.prototype = {
     /**
      * @param {string} eventType
      * @param {function(!WebInspector.Event)} listener
@@ skipping 16 matching lines @@
      */
     hasEventListeners: function(eventType) { },
 
     /**
      * @param {string} eventType
      * @param {*=} eventData
      * @return {boolean}
      */
     dispatchEventToListeners: function(eventType, eventData) { },
 }