This is a how to question as not many information is available. I do, however, took the time out to investigate and tried their simple Hello World app which works great.
Now I tried to use Polymer Starter Kit git clone along with the Hello World tutorial, except for the git clone.
In my testapp folder, for the starter kit, I have added an app.yaml. Inside has the same config as the hello world:
runtime: nodejs
vm: true
api_version: 1
To deploy: gcloud preview app deploy app.yaml --set-default
After all that has completed, it gave me the url to preview the app. Note that the starter kit works on my local machine. The url gave me 503. So I waited for an hour and same 503. In my Dev Console - VM Instances, under Name, I see many instances. Is that correct? Is there a tutorial to get the starter kit on Google Cloud Platform running on nodejs?