[js] avoid temp var when inlining Reflect.callMethod in Type.createEnum

std/js/_std/Type.hx

@@ -112,7 +112,7 @@ enum ValueType {
 		if( f == null ) throw "No such constructor "+constr;
 		if( Reflect.isFunction(f) ) {
 			if( params == null ) throw "Constructor "+constr+" need parameters";
-			return Reflect.callMethod(e,f,params);
+			return Reflect.callMethod(e,(f : haxe.Constraints.Function),params);
 		}
 		if( params != null && params.length != 0 )
 			throw "Constructor "+constr+" does not need parameters";