Replace all implicit Handle<T>(T*) constructors in src/bootstrapper.cc
with explicit ones that use a local variable or parameter.

(All done using Leszek's awesome new tool!)

Bug: v8:7786
Change-Id: Iec01fda502dd121bc1815d5dab73bd09bb3e5aa6
Reviewed-on: https://chromium-review.googlesource.com/1107697Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53873}