fix: tooltip unit test

[dorianmiller]

What do these changes do/fix?

Because of overnight, unit tests were broken. This is the fix to define DOMRect

How do you test/verify these changes?

Run unit test. On Mac M1, consider running this to build canvas:

1. nvm use && nvm install
2. brew install pkg-config cairo pango libpng

Have you documented your changes (if necessary)?

NA

Are there any breaking changes included in this pull request?

No

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