Prevent Tooltip flickering by updating Positioner

[brandongregoryscott]

Overview

This PR addresses #1548 where a flickering issue was introduced in the Portal/Positioner in #1517. I tested out the change in both the example repo listed in #1512 to verify SSR still works, and a personal project to verify the Tooltip isn't flickering - I couldn't reproduce the issue in Storybook.

I believe the issue is caused from the extra render introduced (this.forceUpdate()) - telling the Positioner to update once the Transition state is entering sets the correct dimensions and x/y points before rendering the children.

Screenshots (if applicable)

Rendering	Before	After
CSR
SSR

Documentation

• [ ] Updated Typescript types and/or component PropTypes
• [ ] Added / modified component docs
• [ ] Added / modified Storybook stories

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