[3.2] Bubble media queries

[xzyfer]

This PR implements bubbling and merging of media queries (#185).

To get this over the line I enlisted the help of @hugogiraudel to buff up our @media bubbling spec coverage.

TODO

• hoisting
• media_level_4
• media_wrapper_selector
• mixin
• merge_no_repeat
• selector_wrapper_media
• maintain the correct indentation for nested output mode

This PR also smartens the logic around when to output some types blocks i.e. never output a ruleset that only has unresolved %placeholder selectors. I also fixes some inconsistencies in the nested output for media queries.

As a side affect of these fixes the following tests an outstanding @extends spec now also passes.

Bonus

This the cssize visitor added will also for the basis of @at-root!!!

---

This PR is ready to go for 3.2!

[xzyfer]

I appear to be having issues with the autotools builds https://travis-ci.org/sass/libsass/jobs/45523757

[mgreter]

Did you add your new source files to Makefile.am?

[xzyfer]

You're right I missed that file. That got me closer now I'm getting

./.libs/libsass.so: undefined reference to `Sass::Cssize::fallback_impl(Sass::AST_Node*)'

with the AUTOTOOLS=yes COVERAGE=no BUILD=shared build. I'm not sure what I'm missing. I'll keep digging.

[xzyfer]

This is as good as it is gets. It's ready to go in 3.2 as soon as I can track down the compilation error in AUTOTOOLS=yes COVERAGE=no BUILD=shared

[QuLogic]

Fails in Windows as well:

context.obj : error LNK2019: unresolved external symbol
"private: class Sass::Statement * __thiscall Sass::Cssize::fallback_impl(class Sass::AST_Node *)"
(?fallback_impl@Cssize@Sass@@AAEPAVStatement@2@PAVAST_Node@2@@Z) referenced in function
"public: class Sass::Statement * __thiscall Sass::Cssize::fallback<class Sass::AST_Node *>(class Sass::AST_Node *)"
(??$fallback@PAVAST_Node@Sass@@@Cssize@Sass@@QAEPAVStatement@1@PAVAST_Node@1@@Z) [C:\projects\libsass\win\libsass.vcxproj]

so maybe this points you in the right direction.

[QuLogic]

Probably make this public or protected, I think?

[xzyfer]

I'm not sure why this cause compilation to fail on only some platform though. More this file is just a modified version of eval.hpp

Which declares this as protected.

[coveralls]

Coverage decreased (-0.27%) when pulling 1751f20 on xzyfer:feat/bubble-media-queries into 5045bce on sass:master.

[coveralls]

Coverage decreased (-0.16%) when pulling f69a76b on xzyfer:feat/bubble-media-queries into 5045bce on sass:master.

[xzyfer]

Superseded by #800.