Fixes #2382. Nested views throws TopologicalSort exception if they reference Pos/Dim to the root view.

[BDisp]

Fixes #2382 - When the root of the nested views is valid, so not null, the exception must not throw.

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[tig]

@BDisp would you categorize this as a "critical bug that must be fixed in v1"?

If not, can we just focus it on v2 and leave it be in v1?

[BDisp]

Yes its critical for v1 too. I already made these changes in your critical setrelativelayout-improvments branch.

[BDisp]

@tig if you merge my PR to your critical changes branch and merge it to the develop, we can close this one. I couldn't do a cherry pick because they have different versions. After that we all be focused on the V2. Do you agree?

[BDisp]

Closing this because it was included in the v2 on PR #2385.