Port 378b6b22

Original Commit Message:

    Since we OSR code rarely, it makes sense to store it and look for
    it on the native context rather than the SharedFunctionInfo.
    This makes the OptimizedCodeMap data structure more space efficient,
    as it doesn't have to store an ast ID for the OSR entry point.

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

Review-Url: https://codereview.chromium.org/2557113002
Cr-Commit-Position: refs/heads/master@{#41562}