Break dependency on core from generated mojom.js files

mojo/bindings/js/handle.cc

Index: mojo/bindings/js/handle.cc
diff --git a/mojo/bindings/js/handle.cc b/mojo/bindings/js/handle.cc
index 36a49886db4b39693d26fa66b9298b254007a77d..e1d0fb04b60c063466536c04f48502c7b1423179 100644
--- a/mojo/bindings/js/handle.cc
+++ b/mojo/bindings/js/handle.cc
@@ -17,12 +17,19 @@ HandleWrapper::~HandleWrapper() {
 
 v8::Handle<v8::Value> Converter<mojo::Handle>::ToV8(v8::Isolate* isolate,
                                                     const mojo::Handle& val) {
+  if (!val.is_valid())
+    return v8::Null(isolate);
   return HandleWrapper::Create(isolate, val.value()).ToV8();
 }
 
 bool Converter<mojo::Handle>::FromV8(v8::Isolate* isolate,
                                      v8::Handle<v8::Value> val,
                                      mojo::Handle* out) {
+  if (val->IsNull()) {
+    *out = mojo::Handle();
+    return true;
+  }
+
   gin::Handle<HandleWrapper> handle;
   if (!Converter<gin::Handle<HandleWrapper> >::FromV8(isolate, val, &handle))
     return false;