De-flake fast/multicol/split-in-top-margin.html

De-flake fast/multicol/split-in-top-margin.html

Cannot really trust Ahem. It behaves differently on different platforms.
Set a line height instead, and bottom-align the inline-block, so that we
don't have to worry about a descender of unpredictable height.
Use regular blocks in the ref.

Modified the second test slightly (reduce height by 1px), so that the
line doesn't quite fit (which was typically the case before my
changes, because of the descender, which by the way was assumed
to be 3px in the test expectation).

BUG=438757
R=dsinclair@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186466

[dsinclair, 2014-12-04 00:10:24]

The CQ bit was checked by dsinclair@chromium.org

[dsinclair, 2014-12-04 00:10:24]

lgtm

[commit-bot: I haz the power, 2014-12-04 00:11:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/756203005/1

[commit-bot: I haz the power, 2014-12-04 01:24:09]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=186466