Remove DevTools instrumentation of Blink promises.

This is a dead code now since we moved from Blink promises to V8 ones.

BUG=348919,352597
TBR=yhirano@chromium.org, amikhaylova@google.com

Review URL: https://codereview.chromium.org/297683002

git-svn-id: svn://svn.chromium.org/blink/trunk@174378 bbb929c8-8fbe-4397-9dbb-9b2b20218538