extra build system to get it working

src/core/Matrix4.js

@@ -11,6 +11,8 @@
 
 THREE.Matrix4 = function ( n11, n12, n13, n14, n21, n22, n23, n24, n31, n32, n33, n34, n41, n42, n43, n44 ) {
 
+    this.elements = new Float32Array(16);
+
 	this.set(
 
 		( n11 !== undefined ) ? n11 : 1, n12 || 0, n13 || 0, n14 || 0,