SVG 1.1 dynamic update tests
Tests dynamic updates of the 'y' property of the SVGMaskElement object
On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
PASS maskElement.y.baseVal.valueAsString is "-100%"
PASS maskElement.y.baseVal.valueAsString is "-10%"
PASS successfullyParsed is true
TEST COMPLETE