The fit property does not belong to the enyo.Control kind, it can only be used inside a fittable kind. So change your apps kind to "FittableColumns" or "FittableRows" (or set layoutKind of "FittableColumnsLayout" or "FittableRowsLayout"), like this:
enyo.kind({
name: 'App',
kind: 'FittableColumns',
/* or:
kind: enyo.Control,
layoutKind: 'FittableColumnsLayout', */
components: [
{
name: 'canvas',
kind: enyo.Canvas,
fit: true // works now because of parents fittable layout
}
]
});
I updated your fiddle: http://jsfiddle.net/y9mhE/7/