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

chrome/content/composer.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 {Prefs} = require("prefs");
 
 let domainData;
 let nodeData;
@@ skipping 83 matching lines @@
   };
 }
 
 function createPropertyProxy(obj, orig, key) {
   if (typeof orig[key] == "function") {
     obj[key] = function() {
       return orig[key].apply(orig, arguments);
     };
   }
   else {
-    obj.__defineGetter__(key, function() {
-      return orig[key];
-    });
-    obj.__defineSetter__(key, function(value) {
-      orig[key] = value;
+    Object.defineProperty(obj, key, {
+      get: () => orig[key],
+      set: value => { orig[key] = value; },
+      enumerable: true
     });
   }
 }
 
 function TreeView_getRowProperties(row) {
   let properties = "selected-" + this.selection.isSelected(row);
 
   var item = this.getItemAtIndex(row);
   if (item && (item.nodeData.expression != "*" || item.nodeData == nodeData))
     properties += " anchor";
@@ skipping 124 matching lines @@
             op = "^=";
           else if (attr.value.substr(attr.value.length - attr.selected.length) == attr.selected)
             op = "$=";
   
           let useFallback = false;
           if (attr.name == "id" && op == "=")
             expression += "#" + escapeName(attr.selected).replace(/^([^a-zA-Z\\])/, escapeChar).replace(/\\(\s)$/, escapeChar);
           else if (attr.name == "class" && /\S/.test(attr.selected))
           {
             let knownClasses = {};
-            for each (let cls in attr.value.split(/\s+/))
+            for (let cls of attr.value.split(/\s+/))
               knownClasses[cls] = true;
 
-            let classes = attr.selected.split(/\s+/).filter(function(cls) cls != "");
-            if (classes.every(function(cls) knownClasses.hasOwnProperty(cls)))
+            let classes = attr.selected.split(/\s+/).filter(cls => cls != "");
+            if (classes.every(cls => knownClasses.hasOwnProperty(cls)))
               expression += "." + classes.map(escapeName).join(".");
             else
               useFallback = true;
           }
           else
             useFallback = true;
 
           if (useFallback)
           {
             var escapedValue = attr.selected.replace(/(["\\])/g, '\\$1')
@@ skipping 364 matching lines @@
 
   fillAttributes(item.nodeData);
 }
 
 function addExpression()
 {
   AdblockPlus.addPatterns([document.getElementById("expression").value]);
 
   togglePreview(false);
 }