port 378b6b22 (r41554)

  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.

BUG=

Review-Url: https://codereview.chromium.org/2559083002
Cr-Commit-Position: refs/heads/master@{#41606}