It should be possible to transition from flex() to flex() or from a length to flex() or from flex() to length.
Created attachment 125449 [details] Patch
It looks the test compares the value as a number (float), not a tuple of the numbers. Is it intentional? (Disclaimer: I'm not a flexbox expert.)
Comment on attachment 125449 [details] Patch The spec is changing so this patch isn't correct anymore. I'll post a new patch when we're ready.
Created attachment 135668 [details] Patch
Patch looks good to me. Someone with transitions experience should probably r+ though.
Comment on attachment 135668 [details] Patch Cool!
Comment on attachment 135668 [details] Patch Clearing flags on attachment: 135668 Committed r113264: <http://trac.webkit.org/changeset/113264>
All reviewed patches have been landed. Closing bug.