[css-syntax-3] New parsing algorithms do not handle } tokens correctly in style attributes

[AtkinsSJ]

This WPT test checks that } tokens inside a style attribute are ignored and skipped over. Specifically, these two cases from it fail when following the new parsing algorithms:

<p style="};background:limegreen">This line should have a green background.
<p style="background:red;};background:limegreen">This line should have a green background.

The previous version of the spec says:

"Parse a list of declarations" is for the contents of a style attribute, which parses text into the contents of a single style rule.

That then calls "consume a list of declarations", which when it sees a } token, discards it and the remaining tokens up until the next ;, and then continues parsing the next declaration.

The current draft spec with the new parsing algorithms says:

"Parse a block’s contents" is intended for parsing the contents of any block in CSS (including things like the style attribute), and APIs such as the CSSStyleDeclaration cssText attribute.

However, this now calls "consume a block’s contents" which when it sees a }, immediately exits out and returns the current list of declarations. This makes it fail the above test cases, because declarations after a } are completely ignored.

A Ladybird contributor has proposed a change which seems to restore the previous behaviour - basically by passing an is style attribute flag to "consume a block's contents" and using that to skip over declarations that contain a }.

[cdoublev]

This resonated with me somewhat, so after some digging, it seems the related changes, listed below in chronological order, followed a comment from me:

• ed19498
• 59e4322
• c7ce041
• ea43cbf

In a nested context, } would indeed close the parent rule:

style {
  background:red;
}
/* trash */
; background:limegreen

An orphan } in the style attribute (or the input of CSSStyleDeclaration.cssText) can only be a typo that the new algos do not forgive.