Fix painting order for floats with shape-outside

Fix painting order for floats with shape-outside

When removing the old positioning behavior, the code that makes a float
with shape-outside gain a layer was left behind. This patch removes
that, so now floats with shape-outside are painted just like floats
without shape-outside.  Also remove the isFloatingWithShapeOutside
helper method because its use is now somewhat redundant, and the check
it does is now only needed in one place.

BUG=286448
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157396

[eseidel, 2013-09-06 22:04:19]

lgtm

[commit-bot: I haz the power, 2013-09-06 22:04:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bjonesbe@adobe.com/23866007/1

[commit-bot: I haz the power, 2013-09-06 23:41:50]

Change committed as 157396