Add documentation about the scrolling model
Make sure reftests aren't passing because nothing == nothing

In the test harness, assert that the two images aren't all white.

Fixes #3481
Add support for local font faces. Improves fonts on rust lang and guide.
Allow individual layers to render their own background color

Instead of relying on a scene-wide background color, all layers can now
have their own background color.
script: Use atom comparison in more places, especially for attributes.

75% improvement in style recalc for Guardians of the Galaxy.
auto merge of #3675 : glennw/servo/local-fonts, r=pcwalton
try to reset flows which need reflow, since reflow isn't yet idempotent
auto merge of #3623 : pcwalton/servo/use-atoms-2, r=jdm

75% improvement in style recalc for Guardians of the Galaxy.
auto merge of #3634 : mrobinson/servo/scrolling-doc, r=jdm
layout: Introduce support for legacy presentational attributes to selector
matching, and use it for `<input size>` and `<td width>`.

This implements a general framework for legacy presentational attributes
to the DOM and style calculation, so that adding more of them later will
be straightforward.
auto merge of #3622 : pcwalton/servo/html4ever, r=jdm

This implements a general framework for legacy presentational attributes
to the DOM and style calculation, so that adding more of them later will
be straightforward.
auto merge of #3645 : gilles-leblanc/servo/issue-3481, r=kmcallister

In the test harness, assert that the two images aren't all white.

Fixes #3481
layout: Rewrite intrinsic inline-size and automatic table layout to
match L. David Baron's work-in-progress specification.

    http://dbaron.org/css/intrinsic/

Column spans are not yet supported.

This effectively adds support for percentage widths, and it also fixes
many bugs, improving the layout of Google and Wikipedia.
Implement media queries parser and matching. Improves mobile first sites like bootstrap3.
auto merge of #3609 : pcwalton/servo/tables, r=SimonSapin

http://dbaron.org/css/intrinsic/

Column spans are not yet supported.

This effectively adds support for percentage widths, and it also fixes
many bugs, improving the layout of Google and Wikipedia.

r? @SimonSapin
auto merge of #3640 : cgaebel/servo/incremental-flow-construction, r=pcwalton

This also hides the not-yet-working parts of incremental reflow behind a runtime
flag. As I get the failing reftests passing, I'll send pull requests for them one
by one.
Removes duplicate CSS selector matching logic.

Now that DOM/Flow traversals have been refactored out, the `recalc_style_for_subtree`
function in `css/matching.rs` can be removed, in lieu of just running the standard
`recalc_style_for_node` and `construct_flows` traversals sequentially. Now we
no longer have the maintenance headache of duplicating selector matching logic
in two places! \o/

r? @pcwalton
Uncomments the multiple css class ref-test

This test had been commented out because it was breaking the travis ci
build but was passing locally.

Issue #3681
auto merge of #3610 : glennw/servo/media-queries, r=SimonSapin
auto merge of #3668 : cgaebel/servo/sequential-reflow, r=pcwalton

Now that DOM/Flow traversals have been refactored out, the `recalc_style_for_subtree`
function in `css/matching.rs` can be removed, in lieu of just running the standard
`recalc_style_for_node` and `construct_flows` traversals sequentially. Now we
no longer have the maintenance headache of duplicating selector matching logic
in two places! \o/

This passes reftests with both default arguments, and with `-y 1`.

r? @pcwalton