When only_terminate_in_safe_scope flag is passed as CreateParams for
v8::Isolate, V8 does not trigger intrruption for termination if there
is no explicit SafeForTerminationeScope.
Scope enables termination only in direct v8 calls, any recursive calls
require explicit SafeForTerminationScope.

R=yangguo@chromium.org

Bug: chromium:820640
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: Iac17e30a4b47aa84e70e9218ca0adca9d07f726e
Reviewed-on: https://chromium-review.googlesource.com/1025390Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52793}