This change adds support for the unspecified `-webkit-text-security`
property. All major browsers support this property. The benefit of
adding this property is that the first addition of a prefixed CSS
property will allow us to start running MotionMark.
This depends on servo/stylo#295.
Testing: Three new Servo-specific tests are added for this change. There
are a few `-webkit-text-security` tests in WPT, but they do not seem
to test basic functionality.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
db2a7cbe2a