Remove unused helpers to selectively traverse through only local frames.

This was introduced in https://crrev.com/374212 so find-in-page would
crash less prior to full OOPIF support. It is no longer used and should
be removed.

BUG=none

Review-Url: https://codereview.chromium.org/2119283004
Cr-Commit-Position: refs/heads/master@{#403900}
3 files changed