remove some calls to to-be-deprecated v8::Value::To* functions

extensions/renderer/document_custom_bindings.cc

Index: extensions/renderer/document_custom_bindings.cc
diff --git a/extensions/renderer/document_custom_bindings.cc b/extensions/renderer/document_custom_bindings.cc
index edaed987addc0ab9b2fdd8a374d84e45d35b2227..bb9d7f77023cc7f27e1a2e90da52f978999b5275 100644
--- a/extensions/renderer/document_custom_bindings.cc
+++ b/extensions/renderer/document_custom_bindings.cc
@@ -30,7 +30,7 @@ void DocumentCustomBindings::RegisterElement(
   }
 
   std::string element_name(*v8::String::Utf8Value(args[0]));
-  v8::Local<v8::Object> options = args[1]->ToObject();
+  v8::Local<v8::Object> options = v8::Local<v8::Object>::Cast(args[1]);
 
   blink::WebExceptionCode ec = 0;
   blink::WebDocument document = context()->web_frame()->document();