feat(dart/transform): Support part directives

Allow users to split libraries using the `part` directive.

Closes #1817

modules/angular2/src/core/compiler/directive_lifecycle_reflector.dart

@@ -1,3 +1,5 @@
+library angular2.src.core.compiler.directive_lifecycle_reflector;
+
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
 import 'package:angular2/src/core/compiler/interfaces.dart';
 import 'package:angular2/src/reflection/reflection.dart';

modules/angular2/src/test_lib/test_lib.dart

@@ -100,7 +100,8 @@ class Expect extends gns.Expect {
   void toThrowError([message = ""]) => toThrowWith(message: message);
   void toThrowErrorWith(message) => expectException(this.actual, message);
   void toBePromise() => gns.guinness.matchers.toBeTrue(actual is Future);
-  void toHaveCssClass(className) => gns.guinness.matchers.toBeTrue(DOM.hasClass(actual, className));
+  void toHaveCssClass(className) =>
+      gns.guinness.matchers.toBeTrue(DOM.hasClass(actual, className));
   void toImplement(expected) => toBeA(expected);
   void toBeNaN() =>
       gns.guinness.matchers.toBeTrue(double.NAN.compareTo(actual) == 0);
@@ -139,7 +140,8 @@ class NotExpect extends gns.NotExpect {
 
   void toEqual(expected) => toHaveSameProps(expected);
   void toBePromise() => gns.guinness.matchers.toBeFalse(actual is Future);
-  void toHaveCssClass(className) => gns.guinness.matchers.toBeFalse(DOM.hasClass(actual, className));
+  void toHaveCssClass(className) =>
+      gns.guinness.matchers.toBeFalse(DOM.hasClass(actual, className));
   void toBeNull() => gns.guinness.matchers.toBeFalse(actual == null);
   Function get _expect => gns.guinness.matchers.expect;
 }

modules/angular2/src/transform/common/async_string_writer.dart

@@ -16,7 +16,7 @@ class AsyncStringWriter extends PrintWriter {
       : _curr = curr,
         _bufs = <StringBuffer>[curr];
 
-  AsyncStringWriter() : this._(new StringBuffer());
+  AsyncStringWriter([Object content = ""]) : this._(new StringBuffer(content));
 
   void print(x) {
     _curr.write(x);