Make Cocoa and Nicosia implementations inherit from the base class and move the common code there.
Pull request: https://github.com/WebKit/WebKit/pull/5439
Committed 255731@main (9ab9d3a644c6): <https://commits.webkit.org/255731@main> Reviewed commits have been landed. Closing PR #5439 and removing active labels.
<rdar://problem/101335221>