Fixed StereoEffect.

examples/js/effects/StereoEffect.js

@@ -32,8 +32,8 @@ THREE.StereoEffect = function ( renderer ) {
 
 		var size = renderer.getSize();
 
-		renderer.setScissorTest( true );
 		renderer.clear();
+		renderer.setScissorTest( true );
 
 		renderer.setScissor( 0, 0, size.width / 2, size.height );
 		renderer.setViewport( 0, 0, size.width / 2, size.height );