Bug 1025133. Be more consistent about rounding colors with the skia backend. r=mwoodrow

--HG--
rename : toolkit/devtools/discovery/tests/moz.build => toolkit/devtools/moz.build
extra : rebase_source : 2db3c43532a30db90326c3903d8fe5c96d077d97
Bug 1026596. Add ellipse to bezier helper and use it from SVG. r=bas

This is faster and more accurate. Specifically, the old code
would produce non-monontic segments which was causing rasterization
differences with skia
Bug 1004363 - IonMonkey: A new value-numbering implementation based on a dom-tree DFS. r=nbp