Whenever an Isolate is available on a variable, field, or method
parameter, use that instead of GetIsolate(). Also convert simple
cases of the one-argument handle constructor to either use an
available Isolate, or use GetIsolate() if their first parameter
is a variable.

Bug: v8:7786
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I52805905a9ca8729615ead78859f43d5e8f605f1
Reviewed-on: https://chromium-review.googlesource.com/1092853
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53629}