kCssPercentSizeProperties top-level constant
The two size properties this package repairs, lower-cased.
flutter_html 3.0.0 does parse both, so neither is missing from the 51 CSS
property names declarationsToStyle() handles. The defect is in the value
grammar instead: ExpressionMapping.expressionToLengthOrPercent
(css_parser.dart) branches on a number, an em, a rem and a length,
and ends return LengthOrPercent(0) for everything else. A
PercentageTerm takes that last branch, so width: 50% becomes a width of
zero logical pixels.
Because both properties are already in the supported set, the sibling utility-class packages never suppress them, and this extension needs no entry in their companion tables. That is the one registry chore this package does not have. The same holds for kCssPercentEdgeProperties.
Implementation
const Set<String> kCssPercentSizeProperties = {'height', 'width'};