Add machinery to Ignition and TurboFan to collect and consume
InternalizedString feedback for abstract and strict equality
comparisons. Here we can turn the comparison into a simple
pointer equality check.

R=jarin@chromium.org
BUG=v8:5786

Review-Url: https://codereview.chromium.org/2609013002
Cr-Commit-Position: refs/heads/master@{#42008}