Merge remote-tracking branch 'upstream/master'
Update path for sync-tests.sh.
Sanitize bugs out of reftest manifests better.
Sync Mozilla tests as of https://hg.mozilla.org/mozilla-central/rev/869971ad9fd6 .
Merge pull request #562 from yunxiaoxie/yunxiaoxie/css3-flexbox

Remove tests of css3-flexbox in work-in-progress
Add reference file for background-clip
Merge remote-tracking branch 'upstream/master'
merge
Correct the reference.

* it shouldn't show a red rectangle
* the text must be included
Fix css3-transform-scale-002 reference.

* should show a green rectangle
* should include the text (to match test)
fixed build errors - a whole bunch of spec links & ref file links
fixed spec links to not be prodefs
Add reference file for background-origin
Move images/ files to support/
Remove useless readme file
Move reftest/ ref files to reference/
Merge pull request #564 from chenxix/chenxix/csswg-test/background-clip

Add reference file for background-clip
merge
Move resource/ files to support/

- Remove two useless images
- Move css3.png to support
Move image files to support/

- Move css-background-3/ images to support/
- Move css-background-3/reference/ images to support/
- Delete duplicated images: yy.png, table-head.jpg in reference/