The CSS Typed OM spec exposes the CSSStyleValue hierarchy to worker global scopes ([Exposed=(Window, Worker, PaintWorklet, LayoutWorklet)]), but Blink only exposed CSSStyleValue, CSSKeywordValue, CSSNumericValue, CSSUnitValue and CSSUnparsedValue to Window and the worklets. As a result these constructors were undefined in Workers, unlike in Firefox and Safari.
Aligns Chrome with the spec's [Exposed] set and removes a cross‑thread inconsistency (these constructors are currently undefined in workers); enables off‑main‑thread CSS value manipulation