I would like to insert a note here
After a couple of days of testing Fennec with pixman libs I noticed
1. Gradient colors used for backgrounds for some sites are less smoother like that
Left is with pixman libs, right without

2.On some tests (like 'mobile HTML 5 rendering' test on http://craftymind.com/guimark2 ) performance is 2x+ slower with pixman libraries

Edit: I don't know how much MicroB will 'like' these libs, but still a test build will be good to be benchmarked