This exposed a few bugs which caused the following tests to behave
incorrectly:
- `tab-size-text-wrap.html`: This previously relied on a bug where we
incorrectly treated `white-space: pre` as allowing text wrapping. The
fix here is to implement the text-wrap CSS shorthand property.
- `execCommand-preserveWhitespace.html`: We don't correctly serialize
shorthand properties. This is covered by an existing FIXME in
`CSSStyleProperties::serialized()`
- `white-space-shorthand.html`: The last 5 subtests here fail as we
don't correctly handle shorthand properties in
`CSSStyleProperties::remove_property()`. This is covered by an
existing FIXME in said function.
94f5a51820