Add `freeze-element-property` scriptlet

@scriptlet freeze-element-property

@description
Conditionally prevent assignment to an element property.

@param property
The property name to freeze.

@param [selector]
Optional. The element must matches `selector` for the prevention to take
place.

@param [pattern]
Optional. A pattern to match against the stringified assigned value. The
pattern can be a plain string, or a regex. Prepend with `!` to reverse the
match condition.

The scriptlet `prevent-innerHTML` is now an alias for
`##+js(freeze-element-property, innerHTML, ...)`