Revert "Changed recursive walk to iterative walk, to prevent StackOverflows."

This reverts commit 14e61db5c1fb2060b8f829497b6d03daec394c88.
Revert "Changed react to build a set of "ancestors" to notify of changes and only notify them of value changes once."

This reverts commit 18491c3db57fe63e802cac357556b4bf81965f4d.