Port 876f37c3

Original Commit Message:

    We reuse most of the infrastructure to set break points, with minor
    differences when we encounter functions where we can only break on entry:
    - PrepareFunctionForBreakPoints simply deopts all functions.
    - Break point objects have the canonical source position 0.
    - Break point is set/checked/cleared via bit on the DebugInfo.
    - Debug::Break do not continue stepping since stepping is implemented via
      regular break points and therefore do not interfere with break on entry.

    I promise to add more tests.

R=yangguo@chromium.org, joransiu@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I0595652adced533c1032a6c3fd64cddfd4e730da
Reviewed-on: https://chromium-review.googlesource.com/909292
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#51186}