We already call Document::invalidate_style_sheets and set
the stylesheet member to a new Stylesheet. This matches the behavior of
Firefox, and means the new CSSStyleSheet you get from accessing .sheet
from JS will be correct instead of stale.
(::get_cssom_stylesheet already tries to use the new Stylesheet, but
MutNullableJS::or_init is called, so if we already created a
CSSStyleSheet we will continue to return that one).
Remove the assert_readonly test and add one to verify that assigning to
CSSStyleRule.style correctly forwards to CSSStyleRule.style.cssText.
We currently test for whether CSSStyleRule.style is read-only by
trying to assign to it; however, the spec has it as actually:
interface CSSStyleRule : CSSRule {
...
[SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
};
See: https://drafts.csswg.org/cssom/
The `PutForwards=cssText` means that assigning to CSSStyleRule.style
should actually assign to style.cssText.
Correctly handle unserializable shorthand
get_shorthand_appendable_value doesn't always return a serializable value. This change makes it handle that case correctly.
This change also updates step number in property_value_to_css to reflect the latest spec.
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