Support multiline style attributes

[50Wliu]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions

Description of the Change

Supports style attributes that span multiple lines.

Alternate Designs

None.

Benefits

Multiline style attributes will end correctly and also be tokenized as CSS.

Possible Drawbacks

I foresee none.

Applicable Issues

Fixes #194

[50Wliu]

310f82b uses slightly more incorrect scoping (line-by-line rather than full multiline), but prevents runaway CSS highlighting when semicolons are missing.