Describe the bug:

vertical-align property doesn't work as expected.

HTML to reproduce the issue:

<span>3</span><span style="vertical-align: super">x</span><span>-27 = 0<sup>x</sup></span>

Html widget configuration:

Using clean Html or SelectableHtml.

Additional info:

I couldn't find the property vertical-align in the parser file:

I try to put it, like this, seems works fine in Html default constructor

case 'vertical-align':
  style.verticalAlign =
      ExpressionMapping.expressionToVerticalAlign(value.first);
  break;

// ... //

static VerticalAlign expressionToVerticalAlign(css.Expression value) {
  if (value is css.LiteralTerm) {
    switch (value.text) {
      case "sub":
        return VerticalAlign.SUB;
      case "super":
        return VerticalAlign.SUPER;
    }
  }
  return VerticalAlign.BASELINE;
}

but that doesn't work with the SelectableHtml constructor, throwing a exception in this cast:

i think its are related to flutter/flutter#38474, since it is merged, it's a leftover? removing this cast, works fine in my test case.

A picture of a cute animal (not mandatory but encouraged)