Add new cloneable flag to ShadowRootInit and set it by default for declarative Shadow DOM.
Pull request: https://github.com/WebKit/WebKit/pull/7669
Committed 257978@main (d7d9268e700a): <https://commits.webkit.org/257978@main> Reviewed commits have been landed. Closing PR #7669 and removing active labels.
<rdar://problem/103436986>