DevTools: Highlight changed scope variables as they change

Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js

Index: Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js
diff --git a/Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js b/Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js
index 1180e98e48442091053aaa7e9ada5a931687d40c..bad9bebec7bcd2739767c56f6d2c6a29d469cbdd 100644
--- a/Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js
+++ b/Source/devtools/front_end/sources/WatchExpressionsSidebarPane.js
@@ -36,7 +36,10 @@ WebInspector.WatchExpressionsSidebarPane = function()
 {
     WebInspector.SidebarPane.call(this, WebInspector.UIString("Watch Expressions"));
 
-    this.section = new WebInspector.WatchExpressionsSection();
+    /** @type {!WebInspector.ObjectPropertiesMemento} */
+    this.memento = new WebInspector.ObjectPropertiesMemento();
+
+    this.section = new WebInspector.WatchExpressionsSection(this.memento);
     this.bodyElement.appendChild(this.section.element);
 
     var refreshButton = this.titleElement.createChild("button", "pane-title-button refresh");
@@ -100,12 +103,16 @@ WebInspector.WatchExpressionsSidebarPane.prototype = {
 /**
  * @constructor
  * @extends {WebInspector.PropertiesSection}
+ * @param {!WebInspector.ObjectPropertiesMemento} memento
  */
-WebInspector.WatchExpressionsSection = function()
+WebInspector.WatchExpressionsSection = function(memento)
 {
     this._watchObjectGroupId = "watch-group";
 
     WebInspector.PropertiesSection.call(this, "");
+
+    this.memento = memento;
+
     this.treeElementConstructor = WebInspector.ObjectPropertyTreeElement;
     this.skipProto = false;
 
@@ -222,6 +229,8 @@ WebInspector.WatchExpressionsSection.prototype = {
      */
     updateProperties: function(properties)
     {
+        this.memento.forgetProperties();
+
         this.propertiesTreeOutline.removeChildren();
         WebInspector.ObjectPropertyTreeElement.populateWithProperties(this.propertiesTreeOutline, properties, [],
             WebInspector.WatchExpressionTreeElement, WebInspector.WatchExpressionsSection.CompareProperties, false, null);