Merge branch 'stable-3.2'

This unreverts "Revert "Add Polymer 3 support"".

* stable-3.2:
  Upgrade Gerrit API to 3.2.10
  Revert "Add Polymer 3 support"
  Upgrade Gerrit API to 3.1.15
  Update Gerrit API to 3.0.16
  Update Gerrit API to 2.16.27
  Upgrade Gerrit API to 3.1.12
  Update Gerrit API to 3.0.15
  Update Gerrit API to 2.16.26

Change-Id: I71a5b6fd0f98031f541e41694812982958b8f9b9