
Add support for transition end events now that we are using CSS
transitions all over for Kennedy.

R=chrishenry
DELTA=6  (5 added, 0 deleted, 1 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=3568


yamadatomonori/closure-library,yamadatomonori/closure-library,yamadatomonori/closure-library