The region lines text parsing test is failing.
Some of the assertions pass but some fail due to the usage of very large number values. Safari is clamping the value to the max integer value while Firefox returns a 0. The spec just says to interpret the value as an integer but provides no guidance on it. This potentially means there's no way to test these edge cases. Though, may not be necessary.
Firefox's strict parser and Safari's non-standard implementations prevent the test from passing.