Saturation mousemove listener not working when picker in shadow dom

When rendering Saturation component in shadow dom, mousemove event won't emit.
[This commit](https://github.com/casesandberg/react-color/commit/1cd7a7e2b67e521cedade4420c921f4bbc752dd0) caused an issue.

Start by inspecting the Saturation component and the linked commit that introduced the regression. Reproduce the component inside a shadow DOM and trace the mousemove handling; the issue is done when mousemove events emit there as they do outside shadow DOM.

Written by the indexing model from the issue text.