Port 3a9152ec

Original Commit Message:

    We are planning to add a few more debugger related bits, and are running
    out of compiler hints bits. The new bit field is going to be part of the
    debug info struct. If the debug info is not available, we store the bit
    field in its place on the shared function info.

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

Review-Url: https://codereview.chromium.org/2653673002
Cr-Commit-Position: refs/heads/master@{#42608}