[Extensions] Have Binding inherit from null proto

extensions/renderer/resources/binding.js

Index: extensions/renderer/resources/binding.js
diff --git a/extensions/renderer/resources/binding.js b/extensions/renderer/resources/binding.js
index 60d85a97afa38731403fb18afb2e0350f3b12598..4509f26c98632b0ea8b640f15e118fe9c9a4ea2f 100644
--- a/extensions/renderer/resources/binding.js
+++ b/extensions/renderer/resources/binding.js
@@ -179,7 +179,6 @@ var platform = getPlatform();
 function Binding(apiName) {
   this.apiName_ = apiName;
   this.apiFunctions_ = new APIFunctions(apiName);
-  this.customEvent_ = null;
   this.customHooks_ = [];
 };
 
@@ -188,6 +187,17 @@ Binding.create = function(apiName) {
 };
 
 Binding.prototype = {
+  // Sneaky workaround for Object.prototype getters/setters - our prototype
+  // isn't Object.prototype. SafeBuiltins (e.g. $Object.hasOwnProperty())
+  // should still work.
+  __proto__: null,
+
+  // Forward-declare properties.
+  apiName_: undefined,
+  apiFunctions_: undefined,
+  customEvent_: undefined,
+  customHooks_: undefined,
+
   // The API through which the ${api_name}_custom_bindings.js files customize
   // their API bindings beyond what can be generated.
   //