Combine resize events for each pipeline and process when layout is idle
auto merge of #928 : kmcallister/servo/resize, r=pcwalton
Remove unused resize_rate_limiter.rs

It has bitrotted and we handle this in script_task.rs now.
auto merge of #927 : pcwalton/servo/image-src-set, r=pcwalton

r? @metajack
auto merge of #929 : kmcallister/servo/rm-resize-limiter, r=metajack

It has bitrotted and we handle this in script_task.rs now.
Remove unused variable and parameter
Use is_float.is_some() instead of !is_float.is_none().
auto merge of #931 : sammykim/servo/issue906, r=jdm

Fix #906
auto merge of #933 : saneyuki/servo/is_some, r=jdm

Fix #919
main: Implement pinch zooming on Mac