Add tests to ensure no RFH/RVH objects leak on cross-process navigation

These tests were written as part of https://codereview.chromium.org/1150793002/
which failed on Win8 Aura. Splitting only the test into a separate CL
so it can be committed independently.

BUG=357747

Review URL: https://codereview.chromium.org/1145073004

Cr-Commit-Position: refs/heads/master@{#331138}
2 files changed