Fix Vector3.divideSelf, previously it called an undefined method.

src/core/Vector3.js

@@ -130,7 +130,11 @@ THREE.Vector3.prototype = {
 
 	divideSelf : function ( v ) {
 
-		return this.divide( this, v );
+		this.x /= v.x;
+		this.y /= v.y;
+		this.z /= v.z;
+
+		return this;
 
 	},