Fix Chromium issue 41089999: SVG attribute value matching should be case sensitive when applying style

[hjanuschka]

Chromium Issue

https://issues.chromium.org/issues/41089999

Description

Fixed a long-standing spec compliance bug where Blink applied ASCII case-insensitive attribute value matching to SVG (and other empty-namespace) elements when it should only apply to HTML elements. Selectors like [color="RED"] were incorrectly matching <circle color="red"> in SVG.

CLs involved

1. https://chromium-review.googlesource.com/c/chromium/src/+/7956604
   Match SVG attribute values case-sensitively when applying style. Legacy ASCII case-insensitive attribute value matching now requires the element to be an HTML element, not just in an HTML document, so SVG and empty-namespace elements compare attribute values case-sensitively.
2. https://chromium-review.googlesource.com/c/chromium/src/+/8010611
   Reland of the above with a hot-path fix: attr_case_insensitive is precomputed once in FillMissingData() and stored on the query, avoiding a per-element RuntimeEnabledFeatures lookup and restoring blink_perf.parser/query-selector-all-class performance.

Demo

https://static.januschka.com/i-41089999/

Status

Both CLs merged.