refactor: code cleanup

Closes #1061
feat(element binder): Two way binding for Web Components

Closes #1282
chore(presubmit): Do not use the g3v1x task for presubmit

Closes #1214
chore(release): v0.13.0

(see the v0.13.0 tag for the exact history of this version)
fix(web components): Support Polymer quirks

Closes #1292