Update submodules and ~str/String, to_owned/to_string, & cast/mem to get android building.
auto merge of #2628 : luqmana/servo/up, r=mbrubeck
Update layers submodule for AMD GPU fix.
Add rust-phf to servo build.
auto merge of #2647 : glennw/servo/issue-2462, r=metajack
Prepare makefile.backup for snashot changes
auto merge of #2648 : Manishearth/servo/makefile.backup, r=jdm
auto merge of #2644 : glennw/servo/add-phf, r=metajack
Don't fail on clearing nonexistant timeouts
Fix the assertion failure with inserting node contains child which has id into the document

https://github.com/mozilla/servo/issues/2630
auto merge of #2634 : saneyuki/servo/fix, r=Ms2ger

Fix: #2630
auto merge of #2646 : Manishearth/servo/cleartimeout-opt, r=jdm
Use downloaded snapshots instead of in-tree rust. Also a working linux travis conf