google/tracing-framework — pull request #137 by benvanik (2012-12-18 18:11:00+00:00)
Title: Adding a static wtf.trace.scopeLeave to make it easier to write custom

scope management code.
This means that instead of if (!scope) { scope.leave(); } one can just
use wtf.trace.leaveScope(scope). This also helps the compiler by having
goog.nullFunction and goog.identityFunction used instead of custom mock
objects.