Don't use legacy time base for RAF callback

Legacy timer was never implemented on Worker.RAF, so we always return
the same value for both. Since they are identical, we might as well not
use "legacy".

Bug: 995235
Change-Id: I370171b6b2a082bbc850cd35956244b191611f0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1796083
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Auto-Submit: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695649}

third_party/blink/renderer/core/workers/worker_global_scope.cc

@@ -566,7 +566,7 @@ int WorkerGlobalScope::requestAnimationFrame(V8FrameRequestCallback* callback,
   auto* frame_callback =
       MakeGarbageCollected<FrameRequestCallbackCollection::V8FrameCallback>(
           callback);
-  frame_callback->SetUseLegacyTimeBase(true);
+  frame_callback->SetUseLegacyTimeBase(false);
 
   int ret = animation_frame_provider_->RegisterCallback(frame_callback);