Reverting Vector3.angleTo change. See mrdoob#7343.

mrdoob · mrdoob · commit 4e9abd1fd2ad · 2015-10-15T11:57:15.000-04:00
diff --git a/src/math/Vector3.js b/src/math/Vector3.js
@@ -655,7 +655,7 @@ THREE.Vector3.prototype = {
 
 	angleTo: function ( v ) {
 
-		var theta = this.dot( v ) / Math.sqrt( this.lengthSq() * v.lengthSq() );
+		var theta = this.dot( v ) / ( this.length() * v.length() );
 
 		// clamp, to handle numerical problems
 
