This check skips inserting a breakpoint into the BreakPointInfo if
it has already been inserted before.

Change-Id: Ic773fe1d6b2351bf6069fa0ff002737bd0b03293
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2253851Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Kim-Anh Tran <kimanh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68447}