Port 5586ecfc

Original Commit Message:

    This decouples the checking of the {kJavaScriptCallCodeStartRegister}
    from the deoptimization checks. We now rely more heavily on the above
    register and should check its validity more broadly. Note that there
    also is a bug fix for the ARM port contained in this change.

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

Change-Id: Ic8b58994b083c6c0ec73173120cedf6391b1c964
Reviewed-on: https://chromium-review.googlesource.com/938522Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#51620}