asCssStyleDeclaration function
Parses dynamic css
as CssStyleDeclaration.
Implementation
CssStyleDeclaration asCssStyleDeclaration(dynamic css) {
if (css == null) return CssStyleDeclaration();
if (css is CssStyleDeclaration) return css;
if (css is String) return CssStyleDeclaration()..cssText = css;
if (css is Function) return asCssStyleDeclaration(css());
throw StateError("Can't convert to CSS: $css");
}