To stop the warning above, platform views need to set the style.width and
style.height of their root element to any appropriate (non-null) value.

For example, to make the root html.Element fill all the available space
allocated by the framework, set its style.width and style.height properties
to '100%':

ui

platformViewRegistry

registerViewFactory

viewType

int

viewId

final

html

Element

htmlElement

html

DivElement

()

// ..other props

style

width

'100%'

style

height

'100%'

// ...

return

htmlElement

});