As part of this, we also update all InvokeFunctionCode callers to pass
ecx as the expected-argc register.

Drive-by: Inline InvokeFunction overload into its single use.

Bug: v8:6666
Change-Id: I67590ecc3f4981d014642c9e18d3ed6db9831e54
Reviewed-on: https://chromium-review.googlesource.com/1233653
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56040}