Measure the many aspects of HTMLAllCollection

Multiple spec changes to HTMLAllCollection are under discussion:
https://github.com/whatwg/html/issues/775
https://github.com/whatwg/html/pull/780

To help inform the discussion and estimate risk, measure some of the
aspects that are currently not per spec, as well as a few extra bits for
comparison purposes.

BUG=591605

Review URL: https://codereview.chromium.org/1756963002

Cr-Commit-Position: refs/heads/master@{#379484}
4 files changed