Support multiple interrupt requests in v8 API.

There might be a number of clients that would like to
setup an interrupt request on the Isolate.

The patch also deprecates ClearInterrupt API. As long as
the interrupt handler is called outside of locks there's no way
to guarantee that the handler will not be called after
ClearInterrupt was invoked as it might have already started execution.

Review URL: https://codereview.chromium.org/796623003

Cr-Commit-Position: refs/heads/master@{#25910}