Upgrade to Polymer 0.11.0

TBRing, since this shouldn't be a point of contention. Followed the instructions from [the announcement on Dart Web Development](https://groups.google.com/a/dartlang.org/forum/?utm_medium=email&utm_source=footer#!msg/web/bFdGbFRVVwA/le3m465RJLgJ). Found and patched one probable Polymer bug: #2690.