src/vs/editor/common/config/editorOptions.ts/EditorFloatOption/float
class EditorFloatOption:	public static float(value: any, defaultValue: number): number {
		if (typeof value === 'number') {
			return value;
		}
		if (typeof value === 'undefined') {
			return defaultValue;
		}
		const r = parseFloat(value);
		return (isNaN(r) ? defaultValue : r);
	}