Test that CSSProperty.prototype.overridden is set correctly.


== Running test suite: OverriddenProperty
-- Running test case: OverriddenProperty.effectivePropertyRemoved
color: green;
color: red; overridden

OverriddenStatusChanged event fired.
REMOVED
color: red;


-- Running test case: OverriddenProperty.OverriddenByShorthand
PASS: border-top-color is overridden.
PASS: border-color is NOT overridden.

-- Running test case: OverriddenProperty.OverriddenByImportantShorthand
PASS: border-color is NOT overridden.
PASS: border-top-color is overridden.

-- Running test case: OverriddenProperty.NotOverriddenByImportantLonghand
PASS: border-top-color is NOT overridden.
PASS: border-color is NOT overridden.

-- Running test case: OverriddenProperty.NotOverriddenByLonghand
PASS: border-color is NOT overridden.
PASS: border-top-color is NOT overridden.

-- Running test case: OverriddenProperty.MixedCaseVariablesNotOverridden
PASS: `--foo` is NOT overridden.
PASS: `--FOO` is NOT overridden.