Port 91c88644

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.

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com
BUG=

Review-Url: https://codereview.chromium.org/2011183005
Cr-Commit-Position: refs/heads/master@{#36564}