Dean Johnson pointed out that __contains__ is more Pythonic than the function contained_in. Note that this function had to be reversed for this. self is now the container.
<rdar://problem/36033555>
Created attachment 329267 [details] Patch
Comment on attachment 329267 [details] Patch r=me
Comment on attachment 329267 [details] Patch Clearing flags on attachment: 329267 Committed r225953: <https://trac.webkit.org/changeset/225953>
All reviewed patches have been landed. Closing bug.