Issue 2259 - Removed non-standard JavaScript code from Element Hiding Helper

lib/inspectorObserver.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 let InspectorObserver =
 {
   init: function()
   {
@@ skipping 14 matching lines @@
       gDevTools.off("inspector-ready", this.inspectorReady);
     }.bind(this));
   },
 
   get inspectorButtonTooltip()
   {
     // Randomize URI to work around bug 719376
     let stringBundle = Services.strings.createBundle("chrome://elemhidehelper/locale/global.properties?" + Math.random());
     let result = stringBundle.GetStringFromName("inspector.button.tooltiptext");
 
-    delete this.inspectorButtonTooltip;
-    this.__defineGetter__("inspectorButtonTooltip", function() result);
+    Object.defineProperty(this, "inspectorButtonTooltip", {value: result, enumerable: true});
     return this.inspectorButtonTooltip;
   },
 
   inspectorReady: function(eventName, toolbox, panel)
   {
     let panelWindow = panel.panelWin;
     let inspectBtn = panelWindow.document.getElementById("inspector-breadcrumbs");
     if (!inspectBtn)
       return;
 
@@ skipping 11 matching lines @@
     
     //Override button style for light DevTools theme
     let style = panelWindow.document.createProcessingInstruction("xml-stylesheet", 'href="chrome://elemhidehelper/skin/devToolsOverlay.css" type="text/css"');
     panelWindow.document.insertBefore(style, panelWindow.document.firstChild);
     
     inspectBtn.parentNode.insertBefore(button, inspectBtn);
   }
 };
 
 InspectorObserver.init();