All patching logic is now bundled in one compilation unit.
The CodeSpecialization object is set up by all relocation and patching
that should be applied, and then be run on individual code objects or
the whole instance in one go. We hence only need to iterate all
relocation tables exactly once at instantiation.
Also, we do not patch contexts any more since we do not embed them in
generated code any more.

R=titzer@chromium.org
BUG=v8:5991

Review-Url: https://codereview.chromium.org/2696143006
Cr-Commit-Position: refs/heads/master@{#43324}