rdar://72905725 Add support for installsrc to create a shared source for all platforms to build against. This will allow internal tools to checkout WebKit and run installsrc once then build for multiple platforms.
Created attachment 417231 [details] Patch
Committed r271326: <https://trac.webkit.org/changeset/271326> All reviewed patches have been landed. Closing bug and clearing flags on attachment 417231 [details].