bindings: Add empty checks for toV8()

Source/web/WebDevToolsFrontendImpl.cpp

Index: Source/web/WebDevToolsFrontendImpl.cpp
diff --git a/Source/web/WebDevToolsFrontendImpl.cpp b/Source/web/WebDevToolsFrontendImpl.cpp
index 53675fb4ad7773098af91ee15306289f000c864b..b917a462a4281abc7c8bbd3c536c3ea417015955 100644
--- a/Source/web/WebDevToolsFrontendImpl.cpp
+++ b/Source/web/WebDevToolsFrontendImpl.cpp
@@ -84,6 +84,7 @@ void WebDevToolsFrontendImpl::didClearWindowObject(WebLocalFrameImpl* frame)
         m_devtoolsHost = DevToolsHost::create(this, m_webFrame->frame());
         v8::Local<v8::Object> global = scriptState->context()->Global();
         v8::Local<v8::Value> devtoolsHostObj = toV8(m_devtoolsHost.get(), global, scriptState->isolate());
+        ASSERT(!devtoolsHostObj.IsEmpty());
         global->Set(v8AtomicString(isolate, "DevToolsHost"), devtoolsHostObj);
     }