[Gap Decorations]: Introduce ColumnRuleWidth on ComputedStyle
This CL introduces a new data structure to extend the ColumnRuleWidth
property for the gap decorations feature. Previously, the
column-rule-width property could hold only a single width value.
However, with the gap decorations feature, this property can now hold
multiple values. The CL utilizes the GapDataList template data
structure to store these values in the computed style object.
Additionally, sites that expect a single width value have been updated
to call GetLegacyValue(), which returns the single width.
The CL also updates the parsing logic to return nullptr when no values
are present, allowing the use of the default value.
The code is exercised through the gap-decorations-width-computed.html
test.
Bug: 357648037
Change-Id: I5a28f332c57b16f90d7647c4b601b6eb32f7bb6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5967393
Commit-Queue: Sam Davis Omekara samomekarajr@microsoft.com
Reviewed-by: Alison Maher almaher@microsoft.com
Reviewed-by: Kurt Catti-Schmidt kschmi@microsoft.com
Cr-Commit-Position: refs/heads/main@{#1384732}