Drop Intrusive*TransitionIterators, use recursion instead.
Drop Intrusive*TransitionIterators, use recursion instead.

We already use recursion to iterate over transition trees elsewhere, so this should be safe wrt. call stack height.

Review URL: https://codereview.chromium.org/942523003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#26813}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh