title: VPC "fromLookup" results in all Private Subnets and no Public Subnets
body: <p>Using CDK v1.1.0 I'm trying to create an internet-facing Application Load Balancer.</p>
  
  <p>When I call <code>ec2.vpc.fromLookup</code> using my <code>vpcId</code>, I get all my subnets, but all of them are marked as <code>PRIVATE</code> Subnets. Due to this I get an error that there are no Public Subnets Available. </p>
  
  <p>If I try using <code>ec2.vpc.fromVpcAttributes</code> using my <code>vpcId</code>, <code>availabilityZones</code> and <code>SubnetIDs</code>, I get the error "Cannot read property 'selectSubnets' of undefined".</p>
  
  <p>Route Table of My Subnets: 
  Within the Subnets, my RouteTable has two Routes:</p>
  
  <ul>
  <li>Destination: 10.140.0.0/16, Target: Local, Status Active</li>
  <li>Destination: 0.0.0.0/0, Target: internet-gateway, Status Active</li>
  </ul>
  
  <p>I'm not sure whether my subnet/VPC configuration are incorrect or aws-cdk has a bug. </p>
  
  <p>I've manually tried creating an Application Load Balancer with the public subnets and was able to create is successfully. So I can't say my subnet configs are incorrect. </p>