Vector4.multiply(): remove unnecessary check

src/math/Vector4.js

@@ -227,14 +227,7 @@ class Vector4 {
 
 	}
 
-	multiply( v, w ) {
-
-		if ( w !== undefined ) {
-
-			console.warn( 'THREE.Vector4: .multiply() now only accepts one argument. Use .multiplyVectors( a, b ) instead.' );
-			return this.multiplyVectors( v, w );
-
-		}
+	multiply( v ) {
 
 		this.x *= v.x;
 		this.y *= v.y;