Bug 1030604 - Use nsChangeHint_UpdateOverflow for clip-path and mask changes so we update the PreEffectsBBoxProperty and run the effect on the correct area.  r=roc

The testcase is a slight simplification of dholbert's testcase 2
(attachment 8456312) in the bug.  It fails in the reftest harness
without the patch, and passes in the reftest harness with the patch.
Bug 1038488 patch 1 - Explicitly initialize nsStyleMargin::mCachedMargin and nsStylePadding::mCachedPadding so that it is clear all members of nsStyleFont, nsStyleMargin, nsStylePadding, and nsStyleBorder are explicitly initialized.  r=heycam

While nsMargin does 0-initialize, it's not necessarily obvious that it
does, and I think it's worth making explicit.
Bug 1038488 patch 2 - Remove memset from the operator new of the 4 style structs that have it.  r=heycam

This also moves those 4 operator new methods to be inline to match the
style of all of the others.

I audited that all the members of these structs are initialized by all
their constructors (see patch 1).
Bug 1038488 patch 3 - Use AllocateByObjectID/FreeByObjectID for style structs.  r=heycam