Fix phaserjs#771: make smoothstep(x,a,b) work if a > b

Author: Gaëtan Renaudeau

src/math/Math.js

@@ -1265,18 +1265,7 @@ Phaser.Math = {
     */
     smoothstep: function ( x, min, max ) {
 
-        if (x <= min)
-        {
-            return 0;
-        }
-
-        if (x >= max)
-        {
-            return 1;
-        }
-
-        x = (x - min) / (max - min);
-
+        x = Math.max(0, Math.min(1, (x - min) / (max - min)));
         return x * x * (3 - 2 * x);
 
     },
@@ -1292,18 +1281,7 @@ Phaser.Math = {
     */
     smootherstep: function ( x, min, max ) {
 
-        if (x <= min)
-        {
-            return 0;
-        }
-
-        if (x >= max)
-        {
-            return 1;
-        }
-
-        x = (x - min) / (max - min);
-
+        x = Math.max(0, Math.min(1, (x - min) / (max - min)));
         return x * x * x * (x * (x * 6 - 15) + 10);
 
     },