Reduce code duplication, which breaks jumbo builds. Put the StrictEqual
typing rule into the OperationTyper and share the JSType function,
which is also used by SameValue.

Bug: chromium:779531
Change-Id: If292f319217286fd1c676be04f9de3925ed56965
Reviewed-on: https://chromium-review.googlesource.com/751665Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49088}