Tag attributes with dashes, semicolons or underscores result in parse error

[ademenev]

button.ui.icon.button(data-content="Feeder homing cycle")

error:

no match found, expected: "!=", ")", ",", "=", [ \t] or [._-:a-zA-Z0-9]

The problem is that [._-:a-zA-Z0-9] includes a range (_-:) instead of 3 separate chars. - should be escaped