Don't use a separate channel to communicate window size to the
constellation.

This will make sandboxing much easier since we won't need a
separate Unix pipe just for this.
file_loader: Handle file-not-found and other error conditions
Remove render() bypass for headless mode

render() isn't called in headless mode because the headless compositor never
sends a ReRenderMsg.

(This code was needed originally and that probably changed when CPU rendering
landed, but I'm not sure exactly why.)
Remove WrapNativeParent and nearby cleanup.
Remove Reflectable::GetParentObject.
auto merge of #1198 : Ms2ger/servo/GetParentObject, r=jdm
auto merge of #1182 : pcwalton/servo/no-size-channel, r=metajack

This will make sandboxing much easier since we won't need a
separate Unix pipe just for this.
auto merge of #1195 : kmcallister/servo/headless, r=metajack
Parse `min-width` and `max-width`
Implement max-width, min-width for BlockFlow.
auto merge of #1150 : ILyoan/servo/max_width, r=ILyoan,metajack

For #783, only for block flow.
I'll do the things for other flows as well.

r? @simonsapin, @metajack
Add :any-link (Level 4), :link and :visited selectors.

All links are considered "unvisited" for now.
Remove unneeded clones.
auto merge of #1202 : SimonSapin/servo/link-selectors, r=jdm

All links are considered "unvisited" for now.

In particular, this fixes the UA stylesheet rule that underlines links.
auto merge of #1204 : jdm/servo/clones, r=kmcallister

r? @kmcallister