Let Matrix3.getInverse log an error given a Matrix4.

src/math/Matrix3.js

@@ -171,7 +171,7 @@ THREE.Matrix3.prototype = {
 
 		if ( matrix instanceof THREE.Matrix4 ) {
 
-			console.warn( "THREE.Matrix3.getInverse no longer takes a Matrix4 argument." );
+			console.error( "THREE.Matrix3.getInverse no longer takes a Matrix4 argument." );
 
 		}