Remove the remaining parts of ignorePendingStylesheets and placeholder styles.

Remove the remaining parts of ignorePendingStylesheets and placeholder styles.

This patch is largely just a rename since updateLayoutIgnorePendingStylesheets()
didn't really do anything except call updateLayout() now as nothing was reading
the ignorePendingStyleSheets state, and no callers used the synchronous post
layout task option which was meant for plugins (which Sky doesn't have).

Placeholder styles were related and just add confusion since things pretend to
be display: none while <import>'s are loading. We should expose a real API for
avoiding FOUC instead of pumping frames with display: none elements when
imports are loading.

I had to skip the layout/continuations.sky test since it always crashes now
with an ASSERT failure about a bad cast (filed as bug 446739). The bug already
existed, this patch just makes that one test hit it.

BUG=446739
R=ojan@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/c455e81dbc3404a82f0767a62f507f276d1650fd

[esprehn, 2015-01-07 05:52:12]

esprehn@chromium.org changed reviewers:
+ abarth@chromium.org, ojan@chromium.org

[ojan, 2015-01-07 18:50:44]

lgtm

https://codereview.chromium.org/834693007/diff/20001/sky/tests/TestExpectations
File sky/tests/TestExpectations (right):

https://codereview.chromium.org/834693007/diff/20001/sky/tests/TestExpectatio...
sky/tests/TestExpectations:26: # These tests crash
Nit: Don't need this comment. The line itself makes that clear.

[esprehn, 2015-01-07 18:54:46]

Committed patchset #3 (id:40001) manually as
c455e81dbc3404a82f0767a62f507f276d1650fd (presubmit successful).