Fix invalidation after horizontal insets change

[bryankeller]

Details

When the new experimental optimizations are enabled, we default to invalidating less often. This revealed a case that should have been handled before - if the width or the horizontal insets change, we must invalidate layout metrics the next time prepare runs. Previously, we were only invalidating if the width changed.

This would be a good candidate for a unit test once I add tests for the layout object.

How Has This Been Tested

Airbnb app.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.