Forward the breakpoint iterator to the current position, ignoring
unreachable breakpoints.

R=clemensb@chromium.org

Bug: v8:10147
Change-Id: Ic7e7fca4c69fdea68676ff75031bb5133bfc69d9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2100993
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66716}