There's no class A break point before or after a float.

LayoutBox::classABreakPointValue() should only be called at class A break
points. Document the assertion there, and make sure that
needsForcedBreakBefore() only calls it when at in-flow objects.

BUG=619152
R=eae@chromium.org

Review-Url: https://codereview.chromium.org/2228803003
Cr-Commit-Position: refs/heads/master@{#410703}
3 files changed