Bug 250506

Tokenisation and parsing for whitespaces described in CSS Syntax Module Level 3 matches the current WebKit behavior in custom properties. Some WPTs still have wrong expectations. Both leading and trailing whitespaces should be stripped: https://drafts.csswg.org/css-syntax/#consume-declaration 2. While the next input token is a <whitespace-token>, consume the next input token. ... 7. While the last token in decl’s value is a <whitespace-token>, remove that token." Middle whitespaces collapse to a single <whitespace-token>: https://drafts.csswg.org/css-syntax/#consume-token whitespace Consume as much whitespace as possible. Return a <whitespace-token>.