Add a simple one shot and repeating timer API for Mojo.js.

gin/function_template.h.pump

Index: gin/function_template.h.pump
diff --git a/gin/function_template.h.pump b/gin/function_template.h.pump
index 6c1dbfa2a77ba2689258ca5d58e5c685bc8addea..0a37c68aa65f8b5c82ead6b005d9fdfdefa6cfa2 100644
--- a/gin/function_template.h.pump
+++ b/gin/function_template.h.pump
@@ -141,6 +141,13 @@ inline bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
   return true;
 }
 
+// It's common for clients to just need the isolate, so we make that easy.
+inline bool GetNextArgument(Arguments* args, int create_flags,
+                            bool is_first, v8::Isolate** result) {
+  *result = args->isolate();
+  return true;
+}
+
 
 // DispatchToCallback converts all the JavaScript arguments to C++ types and
 // invokes the base::Callback.