Small optimization in CSS3D molecules example.

Don't need to update scene graph matrices (molecules don't change).

This has very little impact on performance though, bottleneck is not on JS side, profiler shows ~65% of time spent in "(program)".

examples/css3d_molecules.html

@@ -392,6 +392,10 @@
 						object.position.copy( position );
 						object.position.multiplyScalar( 75 );
 						object.billboard = true;
+
+						object.matrixAutoUpdate = false;
+						object.updateMatrix();
+
 						root.add( object );
 
 						objects.push( object );
@@ -432,6 +436,9 @@
 						object.matrix = objMatrix;
 						object.rotation.setEulerFromRotationMatrix( object.matrix, object.eulerOrder );
 
+						object.matrixAutoUpdate = false;
+						object.updateMatrix();
+
 						root.add( object );
 
 						objects.push( object );
@@ -449,9 +456,15 @@
 						joint.matrix.copy( objMatrix );
 						joint.rotation.setEulerFromRotationMatrix( joint.matrix, joint.eulerOrder );
 
+						joint.matrixAutoUpdate = false;
+						joint.updateMatrix();
+
 						var object = new THREE.CSS3DObject( bond );
 						object.rotation.y = Math.PI/2;
 
+						object.matrixAutoUpdate = false;
+						object.updateMatrix();
+
 						object.properties.bondLengthShort = bondLength + "px";
 						object.properties.bondLengthFull = ( bondLength + 55 ) + "px";