[Extensions Bindings] Introduce a supportsLazyListeners property

extensions/renderer/resources/context_menus_handlers.js

Index: extensions/renderer/resources/context_menus_handlers.js
diff --git a/extensions/renderer/resources/context_menus_handlers.js b/extensions/renderer/resources/context_menus_handlers.js
index 0e718c4f5acbc8d1873ed85f1b2a495dc932c798..7e98bcbda0e852fe2169db2eb984cc0fa784ba90 100644
--- a/extensions/renderer/resources/context_menus_handlers.js
+++ b/extensions/renderer/resources/context_menus_handlers.js
@@ -15,13 +15,18 @@ var hasLastError = bindingUtil ?
     require('lastError').hasError;
 
 var jsEvent;
-function createNewEvent(name) {
+function createNewEvent(name, isWebview) {
+  var supportsLazyListeners = !isWebview;
   if (bindingUtil) {
+    var supportsFilters = false;

[lazyboy, 2017/07/14 00:04:42]

Pull this out after line 19 and use it for eventOpts below too?

[Devlin, 2017/07/14 15:37:54]

Wasn't like this previously because supportsFilters is false by default in JS. 
But, doesn't hurt to put it in, so done.

     // Native custom events ignore schema.
-    return bindingUtil.createCustomEvent(name, undefined, undefined);
+    return bindingUtil.createCustomEvent(name, undefined, supportsFilters,
+                                         supportsLazyListeners);
   }
   if (!jsEvent)
     jsEvent = require('event_bindings').Event;
+  var eventOpts =
+      { __proto__: null, supportsLazyListeners: supportsLazyListeners };

[lazyboy, 2017/07/14 00:04:42]

I don't remember style guide put space after {, is this clang format? Does it
work for JS?

[Devlin, 2017/07/14 15:37:54]

I think clang-format doesn't (though JS support for that is still pretty
experimental).  But also our resources files *definitely* don't follow clang
format. :) (though they perhaps should!)  But, in either case, adding in
supportsFilters makes this moot.

   return new jsEvent(name);

[lazyboy, 2017/07/14 00:04:42]

Should we not use eventOpts here?

[Devlin, 2017/07/14 15:37:54]

We should!  Thanks for catching this.  I've expanded the test to catch this as
well (since it would have been a bug).  (I mistakenly thought that
webview.contextMenus.onClick.addListener would have done the trick - apparently
we also need to test webview.contextMenus.create({onclick: function() {}});)

 }
 
@@ -53,7 +58,7 @@ function createContextMenusHandlers(isWebview) {
 
   var contextMenus = { __proto__: null };
   contextMenus.handlers = { __proto__: null };
-  contextMenus.event = createNewEvent(eventName);
+  contextMenus.event = createNewEvent(eventName, isWebview);
 
   contextMenus.getIdFromCreateProperties = function(createProperties) {
     if (typeof createProperties.id !== 'undefined')