layout: Support more types of selectors for style sharing.

This helps avoid problems with style sharing in common cases, often
caused by the user agent stylesheet.
layout: Use the new `append_from` method to get rid of a bunch of moves
in display list construction.

These were showing up in the profile.
layout: Put {ib} splits into a linked list so we stop copying them all
the time.
layout: Stop adding damage when removing whitespace.

Avoids total reflow of the entire document on the maze solver.
auto merge of #3839 : pcwalton/servo/fewer-moves-in-dls, r=glennw

These were showing up in the profile.

r? @glennw
Update azure to remove glfw dependency.
auto merge of #3840 : pcwalton/servo/ib-splits-linked-list, r=glennw

r? @glennw
auto merge of #3841 : pcwalton/servo/removing-whitespace-damage, r=cgaebel

Avoids total reflow of the entire document on the maze solver.

I have tested Wikipedia reflow and it still works.

r? @cgaebel
layout: Promote absolute positioning, floatedness, and clearance into
flags to avoid virtual calls.

These were showing up really high in the maze solver profile.
auto merge of #3843 : pcwalton/servo/flagify-display-and-position, r=glennw

These were showing up really high in the maze solver profile.

r? @glennw
auto merge of #3842 : glennw/servo/update-azure, r=mbrubeck
Update layers, opengles to use the new glx bindings.
auto merge of #3845 : glennw/servo/update-layers-opengles, r=metajack
Update to use CGL crate for mac.
auto merge of #3846 : glennw/servo/cgl, r=metajack
Adding initial version of parser trait

Added parse_chunk method declaration to parser

Removed unnecessary visibilty for parse_chunk function

Implemented parse_chunk function

Implemented parse_chunk fn for ServoHTMLParser

Moved parser trait to mod.rs and added finish fn

added licence header to mod.rs and other review comments

Fixed trailing space issue

Fixed failed tabular space test
layout: Actually calculate restyle damage while styling.

...oops. Looks like I forgot to do this.

r? @pcwalton
auto merge of #3836 : cgaebel/servo/calculate-restyle-damage, r=pcwalton

...oops. Looks like I forgot to do this.

r? @pcwalton
auto merge of #3718 : juzer10/servo/master, r=jdm

We have created parser trait and declared parse_chunk function in this trait. We are yet to implement this parse_chunk for ServoHTMLParser struct.
Disable indexed-browsing-contexts-01.html for flakiness.