Fix flakiness in DumpAccessibilityTree tests with iframes
I found three sources of flakiness in DumpAccessibilityTree tests with iframes:
1. Enabled a check that all frames have loaded before dumping the accessibility
tree. Previously it was only possible to do that check on out-of-process
iframes, but now that bug 532249 is fixed we can do that check on all
iframes.
2. Removed code to check if each frame's surface is ready. It's no longer
necessary now that bug 618120 is fixed, and it was causing flakiness.
3. The scroll max for the main page is sometimes flaky because it changes
asynchronously after the page loads. Modified the tests to not dump
scroll mins and maxes.
Re-enables several disabled tests. We may be able to enable a few more in
a follow-up.
BUG=622387
Review-Url: https://codereview.chromium.org/2289293004
Cr-Commit-Position: refs/heads/master@{#416103}
8 files changed
