This is very strange, why are we initializing the Mojo stuff when creating the main world?

Total %     Symbol Name
100     blink::FrameLoader::dispatchDidClearDocumentOfWindowObject()
100      blink::ScriptController::initializeMainWorld()
100       blink::WindowProxy::initializeIfNeeded()
100        blink::WindowProxy::initialize()
47.6            blink::WindowProxy::createContext()
47.6             v8::NewContext(...)
23.8            content::RenderFrameImpl::didCreateScriptContext(blink::WebLocalFrame*, v8::Local<v8::Context>, int, int)
23.8             extensions::ExtensionFrameHelper::DidCreateScriptContext(v8::Local<v8::Context>, int, int)
23.8              extensions::Dispatcher::DidCreateScriptContext(blink::WebLocalFrame*, v8::Local<v8::Context> const&, int, int)
23.8               extensions::ModuleSystem::ModuleSystem(extensions::ScriptContext*, extensions::ModuleSystem::SourceMap const*)
23.8                content::RenderFrameImpl::EnsureMojoBuiltinsAreAvailable(v8::Isolate*, v8::Local<v8::Context>)
14.3            blink::OriginTrialContext::initializePendingFeatures()
14          blink::WindowProxy::updateDocumentProperty()
14           blink::Document::wrap(v8::Isolate*, v8::Local<v8::Object>)

https://cs.chromium.org/chromium/src/content/renderer/render_frame_impl.cc?q=EnsureMojoBuiltinsAreAvailable&sq=package:chromium&l=2496

Total %		Symbol Name
100	 	content::RenderFrameImpl::EnsureMojoBuiltinsAreAvailable(v8::Isolate*, v8::Local<v8::Context>)
63	 	 mojo::edk::js::Core::GetModule(v8::Isolate*)
63	 	  v8::ObjectTemplate::NewInstance(v8::Local<v8::Context>)
22.4	 	 content::InterfaceProviderJsWrapper::Create(v8::Isolate*, v8::Local<v8::Context>, shell::InterfaceProvider*)
22.4	 	  gin::WrappableBase::GetWrapperImpl(v8::Isolate*, gin::WrapperInfo*)
22.4	 	   v8::ObjectTemplate::NewInstance(v8::Local<v8::Context>)
14.4	 	 mojo::edk::js::Support::GetModule(v8::Isolate*)
14.4	 	  v8::ObjectTemplate::NewInstance(v8::Local<v8::Context>)

All of the time is spent creating the ObjectTemplate's, I wonder how big the mojo bindings are though. It takes even longer than the |document| property which is huge. That makes me think the mojo bindings must be very large?

ex. https://cs.chromium.org/chromium/src/mojo/edk/js/core.cc?q=Core::GetModule&sq=package:chromium&l=386

There's a lot of stuff in there, how do we make that smaller?

Note: The cost of blink::OriginTrialContext::initializePendingFeatures is  issue 637148 . Once we fix that it'll mean the mojo bindings are taking even more time.

Note(2): This is a regression since we added Mojo, we definitely need to do something here. :)