Removes all explicit calls to GetIsolate() in runtime/ by passing it
through calling function functions and implicit calls via the single
argument Handle constructor and handle function.

Bug: v8:7786
Change-Id: I96ac2289a72a42c7abb6754418fecb8e03f2bb29
Reviewed-on: https://chromium-review.googlesource.com/1080528
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53457}