Build libstd etc. with debug info when Servo configured with --enable-debug
Change the mechanism behind summit-crash.html
Move FailureMsg contents into a cloneable struct
Add a helper for sending a message on task failure
Restore failure handling

We probably leak some threads and resources, e.g. when the script task crashes
and doesn't get a chance to send layout data back to layout to be deallocated.

Not tested with iframes yet.
Restore hard-fail mode
Use hard-fail for reftests
Find failure.html relative to exe path, not cwd
auto merge of #1691 : kmcallister/servo/linked-failure, r=pcwalton

We probably leak some threads and resources, e.g. when the script task crashes and doesn't get a chance to send layout data back to layout to be deallocated.

Not tested with iframes yet.