Multiple issues with mx:Tree ( during dynamic updates with XML)

Attached is both a Flex reference example (which works) and the current royale emulation of the same, which demonstrates the issues.

Also see the commit discussion thread at: https://github.com/apache/royale-asjs/commit/acab343f73b939bb3b28a13f9142cba4f799104a

(It is currently possible to enter an infinite loop when opening nodes using the royale example)

**Additional Info**
I will continue to work on unit tests for XML.notification, I believe I was seeing a case in swf where instead of "nodeAdded" here (https://github.com/apache/royale-asjs/blob/649ab783845b4e371b34e182fb6fae5e2574cb1d/frameworks/projects/XML/src/main/royale/XML.as#L2911) it was sending "nodeChanged" instead. I do have a local unit test for this, but I will improve the accuracy of the unit testing as well, because the trackChanges stringification in the current version is less than adequate.

(separate folders in the zip file for flex and royale - each contains a single mxml Application file)
[mxTree_Issue.zip](https://github.com/apache/royale-asjs/files/8768678/mxTree_Issue.zip)