Build some dependencies with rustpkg

Also take a rust-layers bugfix.

In collaboration with Jack Moffitt.
Pass Mac OS version cfg flags to rust-opengles build

This was in the rust-opengles Makefile.in pre-rustpkg.
Update rust-alert to find deps through rustpkg
Update mac platform submodules.
Add CSS overflow property(hidden) test file
Add acid2 test case.
Implemeting help message for servo browser app using groups::opts module.

Signed-off-by: Adenilson Cavalcanti <a.cavalcanti@sisa.samsung.com>
Integrate 'BoxModel' into 'RenderBoxBase'. (#1257)
auto merge of #1278 : saneyuki/servo/rm_box, r=pcwalton
auto merge of #1261 : recrack/servo/add_overflow_testfile, r=pcwalton

Thanks @metajack @ksh8281, @jaeminMoon
Rewrite flow construction to be incrementalizable and parallelizable.

This replaces flow construction with a strict bottom-up tree traversal,
allowing for parallelism. Each step of the traversal creates a flow or
a `ConstructionItem`, similar to how Gecko works. {ib} splits are
handled by not creating `InlineFlow`s until the containing block is
reached.

This should be able to be incrementalized by storing the `Flow` from
layout to layout, and performing fixups during flow construction
and/or wiping containing blocks in a previous pass.
auto merge of #1271 : pcwalton/servo/incremental-reflow, r=larsbergstrom

This replaces flow construction with a strict bottom-up tree traversal,
allowing for parallelism. Each step of the traversal creates a flow or
a `ConstructionItem`, similar to how Gecko works. {ib} splits are
handled by not creating `InlineFlow`s until the containing block is
reached.

This should be able to be incrementalized by storing the `Flow` from
layout to layout, and performing fixups during flow construction
and/or wiping containing blocks in a previous pass.

r? @larsbergstrom
Following suggestion in the merge request, reuse the parameter passed to the
function that has the application name (so in future, if the browser no longer
is named 'servo', the code will continue to work fine).

Signed-off-by: Adenilson Cavalcanti <a.cavalcanti@sisa.samsung.com>
auto merge of #1277 : Adenilson/servo/implementingHelp, r=pcwalton

Executing servo browser for the first time doesn't make evident that it already supports several different flags.

This patch implements a help message displaying the available options and a brief explanation on them, based on comments in source code (opts.rs).

I implemented both short hand/long hand options using getopts::groups.
auto merge of #1287 : june0cho/servo/master, r=pcwalton

Upload acid2 file
add support for transparant png
Fix clean-servo to include clean-style.
Update dependencies.
Port gfx crate to new CF bindings.
Set cfg flags on all rust packages.