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• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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What is the current behavior?

On an edge case where the rootView is not set, onSaveInstanceState will crash the app.

What is the new behavior?

No longer crashes as we check if the rootView exists before using it.

Fixes NativeScript/angular#8.