Fix IllegalStateException on addOrReplaceNewTab

[joshliebe]

Task/Issue URL: https://app.asana.com/0/1200204095367872/1207640706766042/f

Description

• Guards against committing the fragment if onSaveInstanceState has already been called.

Steps to test this PR

• [ ] Code review

[joshliebe]

• #4680 👈
• develop

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