Hide the underlying memory of the PixelBuffer 'Uint8ClampedArray' and move it to the subclass JSPixelBuffer. The plan is to subclass PixelBuffer to a class named 'WebKit::ShareablePixelBuffer'. ShareablePixelBuffer will be created when the software filter appliers run in GPUProcess.
<rdar://problem/94117981>
Pull request: https://github.com/WebKit/WebKit/pull/1261
Committed r295227 (251282@main): <https://commits.webkit.org/251282@main> Reviewed commits have been landed. Closing PR #1261 and removing active labels.