
Replace calls:
goog.mixin(x, new goog.events.EventTarget());

with:
goog.testing.events.mixinListenable(x);

The former will no longer works when we flip the @define
goog.events.Listenable.USE_LISTENABLE_INTERFACE to true.

Please review that the change is as intended above. Since this
is done automatically (with multiple spot-checks), there may be cases
where the output is not as expected. Let me know if you spot any
and I will fix it.

This is part of goog.events leaking listeners elimination
effort

R=mschidlowsky
DELTA=2 (1 added, 0 deleted, 1 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=6244


git-svn-id: 35241bd708fe29f1f6c7a4322d322e99ff93b95e@2498 0b95b8e8-c90f-11de-9d4f-f947ee5921c8

jarib/google-closure-library,Kuniwak/google-closure-library-jsdoc,jarib/google-closure-library,Kuniwak/google-closure-library-jsdoc