chore(example): Add paper-checkbox to the paper demo
chore(karma): Restrict the numbers of files watched for faster startup
chore(example): In the Paper example, make the checkbox less confusing
perf(dccd): Drop useless checks

in _recordAdd(), previous could never be null as the list is never empty
(it has at least a marker).
in _recordRemove(), when the list is composed of a single record, it
must be the record we're trying to remove (and we assert that).

Closes #1256
refactor(dccd): Drop the insertBefore arg from DuplicateMap.put()

Fixes #1128
Closes #1132

The insertBefore argument is never used in the current code
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
doc(change): Add the "Highlights" section to the latest releases
chore(scripts): fail on pipe failures

Closes #922
Closes #1172
Closes #1289
Closes #1291
doc(WebPlatform): improve the inline doc
refactor(WebPlatform): remove an unused property
feat(directive-injector): introduce getFromParent[byKey] methods on DirectiveInjector

First step towards deprecating injector.parent access.

The reason for the deprecation is that performing injector.parent.get
without keeping track of current injector.appInjector is usually wrong
(since the fallback would be injector.parent.appInjector).