Fix HashMap undefined due to missing import

Closes #1280
perf(watch-group): remove expression coalescing

Coalescing is rare but slows down WatchGroup creation.

Closes #1328
refactor(angular.dart): remove undefined export

ShadowRootAware is defined in annotation.dart and not in annotation_src.dart.

Closes #1313
feat: add option to use external css rewriter in template_cache_generator.

The provided rewriter will be used to transform every css read by the
TemplateCache, the original css is provided on stdin, and result is read
from the stdout of provided binary.

TESTING:

The test uses a simple sed script to exercise the integration.

The test runs only if sed is present on the running system.  The test
uses CSS with simple rules that are being translated for RTL locales.

Closes #1052
fix(scope): increase default ScopeDigestTTL to 10 iterations
Revert "perf(dccd): Drop useless checks"

This reverts commit 209d14f29f1dc438f6d5ab8ec1ba9f162f90de60.
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).
feat(probe): add directive getter and export ElementProbe type.

This brings feature parity to ElementProbe with the deprecated Probe
directive.
feat(Context): Add ability to set the Type for the rootScope context
chore(pubspec): use perf_api v0.0.9

This fixes a Travis failure with Dart SDK 1.6.0.dev-8.0 that breaks
master.

  Chrome 37.0.2062 (Mac OS X 10.9.4) ERROR
    Internal error: 'package:perf_api/perf_api.dart': error: line 9 pos 29: expression is not a valid compile-time constant
      final Counters counters = new Counters();