Add tests for the bit_struct! macro.

The macro crate, when built with `--test`,
now depends on itself (a version of itself built without `--test`).
This is a bit unusal, but allows testing a syntax extension.
I did not feel like making a new crate just for this,
and these tests do not belong in any of the other existing crates.
Update to png::Image::pixels as an enum.

https://github.com/servo/rust-png/pull/42

This does *not* fix the issue in #3154, but makes it fail!()
instead of (maybe?) reading uninitalized memory.
Run the same tests for make check on all platforms

This target is no longer run in automation; it's for developer convenience, so
it should really run everything.  Also ensure that `check-all` is a superset
of `check`.
power
Merge pull request #3153 from SimonSapin/bit-struct-tests

Add tests for the bit_struct! macro. r=mbrubeck
Add support for backgrounds on inline elements. Fix fixup() by removing it.

The code that managed ranges was buggy - failing on edge cases
such as a span within a span. I have refactored the code so that the
context information for inline formatting can optionally be stored
within a fragment. This seems cleaner to me, and fixes the bugs
encountered when making these changes by removing the need for
the fixup() functionality (and ranges).
return null from GetNamespaceURI, not the empty string

correctly mark tests
Factor out code to call JS_DeletePropertyById2.

I'll need to write the same code again for cross-origin wrappers.
Enable some of the HTML tests.
Split up web-platform-tests on Travis.
Merge pull request #3100 from Ms2ger/tests-html

Enable some of the HTML tests; r=jdm
Merge pull request #3162 from SimonSapin/png-enum

Update to png::Image::pixels as an enum.
Merge pull request #3168 from Ms2ger/delete_property_by_id

Factor out code to call JS_DeletePropertyById2.
Merge pull request #3145 from wenderen/NamespaceURI.None

return null from GetNamespaceURI, not the empty string; r=Manishearth, Ms2ger
Merge pull request #3167 from LalehB/master

PowerMeasure and Readme in one commit
Merge pull request #3134 from glennw/inline-background

Add support for backgrounds on inline elements. Fix fixup() by removing it.
Merge pull request #3166 from mbrubeck/check

Run the same tests for make check on all platforms
Remove some unneeded pubs
Merge pull request #3161 from mbrubeck/pub

Remove some unneeded pubs. r=Manishearth
Fix <br> support