https://drafts.csswg.org/cssom/#serializing-css-values
"To serialize a CSS component value depends on the component, as follows:
keyword
The keyword converted to ASCII lowercase."
http://bit.ly/2upS0OT
shows that Firefox and Safari serialize shape-rendering 'crispEdges' as 'crispedges', and Edge does not support it.
It also shows 4 other properties that Firefox serializes in lower case, but Blink and Safari serialize in mixed case.
Comment 1 by schenney@chromium.org
, Jul 16