Layer component does not animate in mobile

[brianbancroft]

Expected Behaviour

On mobile devices (or simulated), I would expect the Layer component to animate with the following props provided:

     <Layer
        position="left"
        modal={false}
        onEsc={() => setLayer(false)}
        onClickOutside={() => setLayer(false)}
      >

Actual Behaviour

Only animates in desktop [when the size in ResponsiveContext is not "small"]

https://codesandbox.io/s/grommet-layer-no-animate-mobile-hl9cr?file=/src/Layout.js&resolutionWidth=320&resolutionHeight=675

I am unsure whether this is a bug or is intended behaviour. If intended, I would be happy to change the documentation to make clear this edge.

Steps to Reproduce

1. Check out codesandbox
2. Click Menu icon on top of simulation to trigger the layer

Your Environment

• Grommet version: 2.17.2
• Browser Name and version: Chrome 90.0.4430.93
• Operating System and version (desktop or mobile): MacOS Big Sur 11.2.3

[jcfilben]

Closing since #5274 has been merged

[brianbancroft]

Thanks @g4rry420!