Build: Do not swallow Mako template errors in src/components/style/properties.rs.mako
Build: Ugrade Mako to 0.9.1, to support Python 3.4
Build: Use the same Python for Mako as for DOM codegen.

This defaults to Python 2.x and makes the previous commit useless,
but upgrading Mako doesn’t hurt anyway.
auto merge of #1995 : SimonSapin/servo/mako-py34, r=metajack

On a system where `which python` is Python 3.4.x, the build failed with a very unhelpful error message. The root cause is that Mako 0.8.1 was too old.
Store Window.active_timers in a HashMap

A HashMap allows easily looking up a timer and canceling it in
Window.ClearTimeout.

Fixes #1477.
auto merge of #2002 : mrobinson/servo/issue-1477, r=jdm

A HashMap allows easily looking up a timer and canceling it in
Window.ClearTimeout.

Fixes #1477.
Remove an obsolete comment

Remove a comment that was about a macro that was removed in a7ef1cd35e9347a285f245041db4eb94047f4ab0
auto merge of #2021 : SimonSapin/servo/patch-1, r=jdm

Remove a comment that was about a macro that was removed in a7ef1cd35e9347a285f245041db4eb94047f4ab0
Get rid of match statements in Layout queries.(fixes #2019)
Get rid of match statements in layout queries in script_task
auto merge of #2022 : lpy/servo/issue2019, r=jdm

see #2019