Merge pull request mozilla#4600 from p01/JPX_optimization_2

Optimized JPX decoder ~6% faster

Merge pull request mozilla#4581 from Snuffleupagus/issue-4575

Check that images have valid dimensions (issue 4575)

Merge pull request mozilla#4542 from fkaelberer/typoInSpliceString

Fix typo/unused argument in fontloader.js->spliceString()

Merge pull request mozilla#4420 from prometheansacrifice/RemovingChec…

…kSetPresence

Removing set-presence-in-ImageData check from canvas.js