Fix broken passing of log messages to result of core.UnitTestLogger.endTest()

Fixup to 1b0bc3cf72d670a046cea55a53d875b12a0a7ac0

Closurecompiler could have catched that from the @return definition, possibly too complex.

Compare usage in core.UnitTester.reporter():
                m = r.log[i];
                runtime.log(m.category, m.message);