Clear-out is already done after the allocation, in GraphicsContextGLANGLE.
Pull request: https://github.com/WebKit/WebKit/pull/2404
Committed 252453@main (d7ff53ec3747): <https://commits.webkit.org/252453@main> Reviewed commits have been landed. Closing PR #2404 and removing active labels.
<rdar://problem/97010530>