imageCoverFrame: use widgetSurfaceCache
imageCoverFrame: use widgetSurfaceCache

A big performance win for template B hover states, will save us
from needing to resize images every frame.
[endlessm/eos-sdk#3942]

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib