Fix bug introduced in prev commit
Merge pull request #3756 from ussuri/dynamic-ace-container-element

Fix bug introduced in prev commit
Branch 0.18
Remove no-longer-relevant build script

I was the only user of it ever, and I've settled on an alternative build sequence.
Merge pull request #3757 from ussuri/minor-cleanups

Remove no-longer-relevant build script
Pin Polymer version in templates to `latest`

...now that the GitHub access rate limit is no longer an issue, which was the reason for the original back-and-forth between master-latest-master (master doesn't go through version resolution, so didn't hit the limit). The rate limit was fixed in #3733.
Merge pull request #3758 from ussuri/pin-polymer-in-templates-2

Pin Polymer version in templates to `latest`
Update release notes for 0.18
Merge branch 'upstream-master' into consolidate-ui-in-topUi