Use HashMap::find_with_or_insert_with in DocumentHelpers::register_named_element (fixes #3193)
Update glfw-rs to pick up a build warning fix.
auto merge of #3613 : Ms2ger/servo/glfw, r=jdm
auto merge of #3577 : ttaubert/servo/issue/3193-named-element-mangle, r=jdm

Should probably use HashMap::entry() but that doesn't seem to be available with servo's current rust snapshot.

r? @Ms2ger
Position layers using their absolute position

Layers are currently all children of the root layer, so instead of
using coordinates relative to the parent flow we should use coordinates
relative to the page.

Fixes #2061.
auto merge of #3617 : mrobinson/servo/layer-positioning, r=pcwalton

Layers are currently all children of the root layer, so instead of
using coordinates relative to the parent flow we should use coordinates
relative to the page.

Fixes #2061.
layout: Implement `z-index`.
auto merge of #3599 : pcwalton/servo/z-index, r=glennw

r? @glennw
layout: Mark the styles of elements with pseudos as unshareable.

Makes multiple `<br>` elements work, since those are implemented via
`before` pseudos.
auto merge of #3600 : pcwalton/servo/pseudo-unshareable, r=mbrubeck

Makes multiple `<br>` elements work, since those are implemented via
`before` pseudos.

r? @mbrubeck
Remove unnecessary `deref()`s (fixes #3586)
auto merge of #3620 : ttaubert/servo/issue/3586-remove-derefs, r=Manishearth

r? @Manishearth
layout: Make `box-sizing` only affect explicitly-specified or percentage
sizes, not automatically computed ones.

Improves GitHub significantly.