If opts is retrieved, but not set by platform layer, return a default set.

This is required for unit tests like the image cache task, which can
pass through code paths that query the command line options.
Layout: Fix resize (which just plain doesn't work right now).

Currently, both restyle/flow construction _and_ reflow are skipped
during resize. Reflow should not be in that list. This patch fixes
that.
Run all task spawning through util, to allow for easy hooking.

During debugging, I found it useful to hook all task creation in a
central location, and util::task was the perfect place for it.

r? @pcwalton (or maybe someone else, I'm kinda sending you a bunch of
reviews today because I don't know who better to give them to)
make naming more consistent
layout: Implement flow tree dumping with RUST_LOG=debug is on.

r? @pcwalton
util: Primarily fixes a bug where SmallVec.into_iter just doesn't work.

into_iter used to use `inline_size` as the capacity insetad of the actual
capacity. This patch fixes that, adds some utility methods to `SmallVec`
to bring it closer in functionality to `Vec`, and removes the obsolete
`owns_managed` calls.
auto merge of #3827 : cgaebel/servo/use-custom-spawn, r=pcwalton

During debugging, I found it useful to hook all task creation in a
central location, and util::task was the perfect place for it.

r? @pcwalton (or maybe someone else, I'm kinda sending you a bunch of
reviews today because I don't know who better to give them to)
use println instead of error
combine conditions
remove warning
use size hints
util: Add a method to push all elements from another doubly-linked list
without any moves.

This is tracked upstream as Rust bug #18402.
gfx: Inline a few commonly-used methods that were showing up in profiles
auto merge of #3826 : cgaebel/servo/fix-resize, r=pcwalton

Currently, both restyle/flow construction _and_ reflow are skipped
during resize. Reflow should not be in that list. This patch fixes
that.
auto merge of #3823 : glennw/servo/default-opts, r=mbrubeck

This is required for unit tests like the image cache task, which can pass through code paths that query the command line options.
layout: Make some formatting cleanups.

These should have no effect on functionality.
fix the build
auto merge of #3828 : cgaebel/servo/layout-node-dumping, r=pcwalton

r? @pcwalton
auto merge of #3831 : pcwalton/servo/append-from, r=mbrubeck

This is tracked upstream as Rust bug #18402.

r? @mbrubeck
auto merge of #3832 : pcwalton/servo/display-list-inline, r=mrobinson

r? @mrobinson (or whoever)