Merge r139337 to M25.

Merge r139337 to M25.

  REGRESSION(r136967): margin-top + overflow:hidden causes incorrect layout for internal floated elements
  https://bugs.webkit.org/show_bug.cgi?id=106374

  Reviewed by David Hyatt.

  r136397 treated any self-collapsing block that had a clearance delta as though it was clearing a float, but
  blocks that avoid floats can get a clearance delta too. So just ensure there is clearance on the block when deciding
  whether we need to add the margin back in before placing the float.

TBR=tony@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=140447