Currently GCGLSpan can't be modified after construction. This leads to needing to wrap in a type with interior mutability, such as std::optional<>, if the span needs to be changed. Allowing assignment removes this wart.
<rdar://problem/98818853>
Pull request: https://github.com/WebKit/WebKit/pull/3445
Committed 253574@main (b237a7c11f6f): <https://commits.webkit.org/253574@main> Reviewed commits have been landed. Closing PR #3445 and removing active labels.