Bug 916972 - Eliminate nsIFrame::GetSplittableType() completely. r=mats,dholbert

Currently, GetSplittableType() is called only in
nsCSSFrameConstructor::CreateContinuingFrame(). The splittable concrete frames
should inherit from nsSplittableFrame, and must explicitly create continuing
frame in CreateContinuingFrame(). Thus, no need to maintain GetSplittableType().

Differential Revision: https://phabricator.services.mozilla.com/D10798

layout/tables/nsTableColFrame.cpp

@@ -202,12 +202,6 @@ nsTableColFrame::GetFrameName(nsAString& aResult) const
 }
 #endif
 
-nsSplittableType
-nsTableColFrame::GetSplittableType() const
-{
-  return NS_FRAME_NOT_SPLITTABLE;
-}
-
 void
 nsTableColFrame::InvalidateFrame(uint32_t aDisplayItemKey, bool aRebuildDisplayItems)
 {