Revert "Improve Vector2 closure performance"

This reverts commit 5f2187fbef3960f2111d498adf5e6a8c50404946.

src/math/Vector2.js

@@ -268,11 +268,17 @@ Object.assign( Vector2.prototype, {
 
 	clampScalar: function () {
 
-		var min = new Vector2();
-		var max = new Vector2();
+		var min, max;
 
 		return function clampScalar( minVal, maxVal ) {
 
+			if ( min === undefined ) {
+
+				min = new Vector2();
+				max = new Vector2();
+
+			}
+
 			min.set( minVal, minVal );
 			max.set( maxVal, maxVal );