On the debug info, we have a list of existing break points.  When we
step in the debugger, we flood the function with one-shot break points.
Afterwards, we clear these one-shots by clearing all break locations.

Previously, while clearing break locations, we would skip ones that have
actual break points. Now we clear all break locations, and then reapply
break points. This is necessary for the next step, when we encode break
point info by source position, and not code offset. Encoding by code
offset would mean that break points are dependent on the code kind we
use.

R=jgruber@chromium.org
BUG=v8:5265

Review-Url: https://codereview.chromium.org/2221333002
Cr-Commit-Position: refs/heads/master@{#38492}