Patch in changes for 'Fix for Selection nodes not remaining in sync with Document' 

@Steell PTAL

This is from: https://github.com/DynamoDS/Dynamo/pull/2634/files

I'm not 100% confident of the process I used to regenerate the patch.
Please could you do a merge into your build and check that it's behaving, the commit and merge into both branches.

Thanks!