[gin] Add Arguments::GetAll()

extensions/renderer/event_emitter.cc

Index: extensions/renderer/event_emitter.cc
diff --git a/extensions/renderer/event_emitter.cc b/extensions/renderer/event_emitter.cc
index 79b1e8292091444356d665d6c7eb6a63fd48eb31..ccd4303cedcfcc2c42be654d8d7273d48f7936dd 100644
--- a/extensions/renderer/event_emitter.cc
+++ b/extensions/renderer/event_emitter.cc
@@ -130,11 +130,7 @@ void EventEmitter::Dispatch(gin::Arguments* arguments) {
   v8::HandleScope handle_scope(arguments->isolate());
   v8::Local<v8::Context> context =
       arguments->isolate()->GetCurrentContext();
-  std::vector<v8::Local<v8::Value>> v8_args;
-  if (arguments->Length() > 0) {
-    // Converting to v8::Values should never fail.
-    CHECK(arguments->GetRemaining(&v8_args));
-  }
+  std::vector<v8::Local<v8::Value>> v8_args = arguments->GetAll();

[Devlin, 2017/04/17 21:55:18]

There's a few more places that use this that I'll change in a separate followup,
if this lgty.

   Fire(context, &v8_args, nullptr);
 }