port 91c88644 (r36539)

  original commit message:
  We get less "pollution" of type feedback if we have one vector per native
  context, rather than one for the whole system. This CL moves the vector
  appropriately.

BUG=

Review-Url: https://codereview.chromium.org/2019263002
Cr-Commit-Position: refs/heads/master@{#36570}