Debugger: use debug break slot to break on call.

Debugger: use debug break slot to break on call.

Break point at calls are currently set via IC. To change this, we
need to set debug break slots instead. We also need to distinguish
those debug break slots as calls to support step-in.

To implement this, we add a data field to debug break reloc info to
indicate non-call debug breaks or in case of call debug breaks, the
number of arguments. We can later use this to find the callee on the
evaluation stack in Debug::PrepareStep.

BUG=v8:4269
R=ulan@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1222093007

Cr-Commit-Position: refs/heads/master@{#29561}