Make sure RefCell borrows are temporary.

This fixes two `RefCell<T> is already borrowed` failures when reloading an
existing pipeline, both caused by functions trying to modify `Pipeline::url`
or `ScriptTask::url` while a reference to a previous borrow is still in scope.
Remove unused invalidate_rect code
Implement Element.localName.(fixes #2188)
auto merge of #2209 : lpy/servo/issue2188, r=Ms2ger

see #2188
Update expectations.
auto merge of #2211 : Ms2ger/servo/update-expectation, r=Ms2ger
auto merge of #2208 : mbrubeck/servo/dead-invalidate-rect, r=metajack

This is dead code; should we remove it, or are there plans to use it sometime soon?

r? @pcwalton
auto merge of #2203 : mbrubeck/servo/back-crash, r=jdm

This fixes two `RefCell<T> is already borrowed` failures when reloading an
existing pipeline, both caused by functions trying to modify `Pipeline::url`
or `ScriptTask::url` while a reference to a previous borrow is still in scope.

Note: After applying this patch, there are some painting issues after navigating back.
Convert ~[] to std::vec::Vec in FontStyle and FontGroup
Convert ~[] to std::vec::Vec in main/css
Convert ~[] to std::vec::Vec in main/compositing
~[] to std::vec::Vec in layout
layout/construct converted with Option intact
Null commit
More ~[] to std::vec::Vec in main/layout
More ~[] to Vec in main/layout
~[] to Vec in main/layout/wrapper.rs
~[] to Vec in main/compositing/compositor_layer.rs
~[] to Vec in main/constellation.rs
~[] to Vec in main