Add ScriptPromiseResolver::detach

A ScriptPromiseResolver requires to be resolved or rejected before it is
destructed. One the other hand, some APIs need to "detach" promise in certain
cases, i.e. they need to leave the associated promise pending forever. This
change adds ScriptPromiseResolver::detach for the use case.

BUG=None
R=haraken@chromium.org

Review URL: https://codereview.chromium.org/1696553005

Cr-Commit-Position: refs/heads/master@{#375658}
2 files changed