This is a Browser Action API.
_assertEqual(expected, actual, message)
The parameters are:
_assertEqual("abc", "abc", "Some Log Message");
// does nothing
_assertEqual("abc", "def", "Some Log Message");
// throws exception and writes “Some Log Message” to logs.
_assertEqual will do nothing if the expected and actual values are equal.
_assertEqual will log failures to the playback logs if the expected and actual values are NOT equal.
DO NOT USE THIS IN AN IF CONDITION as it does not return any value, and throws an exception if the expected and actual values are not equal.