InstancedMesh: frustumCulled false by default.

src/objects/InstancedMesh.js

@@ -20,6 +20,8 @@ function InstancedMesh( geometry, material, count ) {
 
 	this.count = count;
 
+	this.frustumCulled = false;
+
 }
 
 InstancedMesh.prototype = Object.assign( Object.create( Mesh.prototype ), {