move decision isBlock/isInline solely to CssWhitespacePolicy

There was a duplication in Stlyes.isBlock() and
AbstractBlockBox.isInline(node). Both methods decided if a node was
block or inline, but they were not consistent. Since the isBlock
property depends also on the display property of the parent node, the
responsibility was moved to the CssWhitespacePolicy. The information in
Styles was not sufficient.

Change-Id: Ic6a9f590009a1749433db0494e14bb7b5be78c89
19 files changed