Previously, when restarting a frame, we would rewrite all frames
between the debugger activation and the frame to restart to squash
them, and replace the return address with that of a builtin to
leave that rewritten frame, and restart the function by calling it.

We now simply remember the frame to drop to, and upon returning
from the debugger, we check whether to drop the frame, load the
new FP, and restart the function.

R=jgruber@chromium.org, mstarzinger@chromium.org
BUG=v8:5587

Review-Url: https://codereview.chromium.org/2636913002
Cr-Commit-Position: refs/heads/master@{#42725}