Remove constexpr from static SpeculationMapping declaration to fix error "non-constexpr function 'fill' cannot be used in a constant expression"
Pull request: https://github.com/WebKit/WebKit/pull/16448
Committed 266668@main (1221211ae67b): <https://commits.webkit.org/266668@main> Reviewed commits have been landed. Closing PR #16448 and removing active labels.
<rdar://problem/113530477>