ExtensionView's constructor takes a parent argument and directly calls `this.show(parent)` at the end of the constructor. This is problematic if you're creating and ExtensionView but you don't want to show it right away or you don't know about its parent element yet. The correct behavior should be the same as for View objects: do not take `parent` as a constructor argument, wait for a call to `extensionView.show(parent)` whenever needed.
Created attachment 154517 [details] Patch
Comment on attachment 154517 [details] Patch LGTM
Comment on attachment 154517 [details] Patch Clearing flags on attachment: 154517 Committed r123753: <http://trac.webkit.org/changeset/123753>
All reviewed patches have been landed. Closing bug.