Bug 839957 - Avoid inaccuracies when computing SVG glyph positions. r=longsonr
Bug 839956 - Choose SVG text font size scale factor without regard to devPixelsPerPx. r=longsonr
Bug 839957 - Followup for review comment.
Bug 858550 - Don't transform fixed layer descendents multiple times. r=nrc

Once the transform for async scrolling has been applied to a fixed layer, it
need not be applied to its descendents. Make sure to return after applying
the transform.
Bug 859749 - Fix building with --enable-dump-painting and --disable-debug. r=mattwoodrow

DisplayItemClip::ToString should be in a MOZ_DUMP_PAINTING #ifdef, rather than
a generic DEBUG #ifdef.