feat(dart/transform): Add a di transformer

Add a transformer for `di` which generates `.ng_deps.dart` files for all
`.dart` files it is run on. These `.ng_deps.dart` files register
metadata for any `@Injectable` classes.

Fix unit tests for changes introduced by the di transformer.

When using `pub (build|serve) --mode=ngstatic`, we will also generate
getters and setters, parse templates, and remove import of `dart:mirrors`
in the Angular transform. Because this is still relatively immature, we
use the mode to keep it opt-in for now.

Closes #700

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

@@ -7,3 +7,4 @@ const REGISTER_TYPE_METHOD_NAME = 'registerType';
 const REGISTER_GETTERS_METHOD_NAME = 'registerGetters';
 const REGISTER_SETTERS_METHOD_NAME = 'registerSetters';
 const REGISTER_METHODS_METHOD_NAME = 'registerMethods';
+const TRANSFORM_MODE = 'ngstatic';

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

@@ -13,9 +13,14 @@ class TransformerOptions {
   /// application's [ReflectionCapabilities] are set.
   final String reflectionEntryPoint;
 
-  TransformerOptions._internal(this.entryPoint, this.reflectionEntryPoint);
+  /// The `BarbackMode#name` we are running in.
+  final String modeName;
 
-  factory TransformerOptions(String entryPoint, {String reflectionEntryPoint}) {
+  TransformerOptions._internal(
+      this.entryPoint, this.reflectionEntryPoint, this.modeName);
+
+  factory TransformerOptions(String entryPoint,
+      {String reflectionEntryPoint, String modeName: 'release'}) {
     if (entryPoint == null) {
       throw new ArgumentError.notNull(ENTRY_POINT_PARAM);
     } else if (entryPoint.isEmpty) {
@@ -24,6 +29,7 @@ class TransformerOptions {
     if (reflectionEntryPoint == null || entryPoint.isEmpty) {
       reflectionEntryPoint = entryPoint;
     }
-    return new TransformerOptions._internal(entryPoint, reflectionEntryPoint);
+    return new TransformerOptions._internal(
+        entryPoint, reflectionEntryPoint, modeName);
   }
 }