refactor(dart/transform): Have DeferredRewriter run in parallel

Previously, `DeferredRewriter` checked for the existence of
`.ng_deps.dart` files to determine which deferred libraries it needed to
rewrite, requiring that those assets exist at the time it was run.

Update to check for `.ng_meta.json` files instead, which exist after the
`DirectiveProcessor` phase. This allows the `DeferredRewriter` (which
only processes *.dart files) to run in
parallel with `TemplateComplier` (which only processes *.ng_meta.json
files) and `StylesheetCompiler` (which only processes *.css files).

Have DeferredRewriter to check existence of .ng_meta.json assets rather than .ng_deps.dart assets

modules_dart/transform/lib/src/transform/deferred_rewriter/rewriter.dart

@@ -7,8 +7,8 @@ import 'package:analyzer/src/generated/ast.dart';
 import 'package:angular2/src/transform/common/asset_reader.dart';
 import 'package:angular2/src/transform/common/logging.dart';
 import 'package:angular2/src/transform/common/names.dart';
+import 'package:angular2/src/transform/common/url_resolver.dart';
 import 'package:barback/barback.dart';
-import 'package:code_transformers/assets.dart';
 import 'package:quiver/iterables.dart' as it;
 
 class Rewriter {
@@ -77,6 +77,7 @@ class _FindDeferredLibraries extends Object with RecursiveAstVisitor<Object> {
   var loadLibraryInvocations = new List<MethodInvocation>();
   final AssetReader _reader;
   final AssetId _entryPoint;
+  final _urlResolver = const TransformerUrlResolver();
 
   _FindDeferredLibraries(this._reader, this._entryPoint);
 
@@ -109,16 +110,17 @@ class _FindDeferredLibraries extends Object with RecursiveAstVisitor<Object> {
     return true;
   }
 
-  // Remove all deferredImports that do not have a ng_dep file
+  // Remove all deferredImports that do not have an associated ng_meta file
   // then remove all loadLibrary invocations that are not in the set of
   // prefixes that are left.
   Future cull() async {
+    var baseUri = toAssetUri(_entryPoint);
+
     // Determine whether a deferred import has ng_deps.
     var hasInputs = await Future.wait(deferredImports
         .map((import) => stringLiteralToString(import.uri))
-        .map((uri) => toDepsExtension(uri))
+        .map((uri) => toMetaExtension(uri))
-        .map((depsUri) => uriToAssetId(_entryPoint, depsUri, logger, null,
+        .map((metaUri) => fromUri(_urlResolver.resolve(baseUri, metaUri)))
-            errorOnAbsolute: false))
         .map((asset) => _reader.hasInput(asset)));
 
     // Filter out any deferred imports that do not have ng_deps.

modules_dart/transform/lib/src/transform/transformer.dart

@@ -36,10 +36,10 @@ class AngularTransformerGroup extends TransformerGroup {
         [new DirectiveProcessor(options)],
         [new DirectiveMetadataLinker()],
         [
-          new TemplateCompiler(options),
+          new DeferredRewriter(options),
           new StylesheetCompiler(),
+          new TemplateCompiler(options)
         ],
-        [new DeferredRewriter(options)]
       ];
     }
     return new AngularTransformerGroup._(phases,

modules_dart/transform/test/transform/deferred_rewriter/complex_deferred_example/hello.ng_deps.dart

@@ -1,22 +0,0 @@
-library playground.src.hello_world.absolute_url_expression_files.ng_deps.dart;
-
-import 'hello.dart';
-export 'hello.dart';
-import 'package:angular2/src/core/reflection/reflection.dart' as _ngRef;
-import 'package:angular2/angular2.dart'
-    show bootstrap, Component, Directive, View, NgElement;
-
-var _visited = false;
-void initReflector() {
-  if (_visited) return;
-  _visited = true;
-  _ngRef.reflector
-    ..registerType(
-        HelloCmp,
-        new _ngRef.ReflectionInfo(const [
-          const Component(selector: 'hello-app'),
-          const View(
-              template: r'''{{greeting}}''',
-              templateUrl: r'package:other_package/template.html')
-        ], const [], () => new HelloCmp()));
-}

modules_dart/transform/test/transform/deferred_rewriter/complex_deferred_example/hello.ng_meta.json

@@ -0,0 +1,32 @@
+{
+  "HelloCmp":
+  {
+    "kind": "type",
+    "value": {
+      "isComponent": true,
+      "dynamicLoadable": true,
+      "selector":"hello-app",
+      "exportAs": null,
+      "type": {
+        "id": 1,
+        "name": "HelloCmp",
+        "moduleUrl": "asset:angular2/test/transform/deferred_rewriter/complex_deferred_example/hello.dart"
+      },
+      "changeDetection": 5,
+      "inputs": {},
+      "outputs": {},
+      "hostListeners": {},
+      "hostProperties": {},
+      "hostAttributes": {},
+      "lifecycleHooks": [],
+      "template": {
+        "encapsulation": 0,
+        "template": "Hi",
+        "templateUrl": "package:other_package/template.html",
+        "styles": null,
+        "styleUrls": null,
+        "ngContentSelectors": null
+      }
+    }
+  }
+}

modules_dart/transform/test/transform/deferred_rewriter/simple_deferred_example/hello.ng_deps.dart

@@ -1,22 +0,0 @@
-library playground.src.hello_world.absolute_url_expression_files.ng_deps.dart;
-
-import 'hello.dart';
-export 'hello.dart';
-import 'package:angular2/src/core/reflection/reflection.dart' as _ngRef;
-import 'package:angular2/angular2.dart'
-    show bootstrap, Component, Directive, View, NgElement;
-
-var _visited = false;
-void initReflector() {
-  if (_visited) return;
-  _visited = true;
-  _ngRef.reflector
-    ..registerType(
-        HelloCmp,
-        new _ngRef.RegistrationInfo(const [
-          const Component(selector: 'hello-app'),
-          const View(
-              template: r'''{{greeting}}''',
-              templateUrl: r'package:other_package/template.html')
-        ], const [], () => new HelloCmp()));
-}

modules_dart/transform/test/transform/deferred_rewriter/simple_deferred_example/hello.ng_meta.json

@@ -0,0 +1,32 @@
+{
+  "HelloCmp":
+  {
+    "kind": "type",
+    "value": {
+      "isComponent": true,
+      "dynamicLoadable": true,
+      "selector":"hello-app",
+      "exportAs": null,
+      "type": {
+        "id": 1,
+        "name": "HelloCmp",
+        "moduleUrl": "asset:angular2/test/transform/deferred_rewriter/simple_deferred_example/hello.dart"
+      },
+      "changeDetection": 5,
+      "inputs": {},
+      "outputs": {},
+      "hostListeners": {},
+      "hostProperties": {},
+      "hostAttributes": {},
+      "lifecycleHooks": [],
+      "template": {
+        "encapsulation": 0,
+        "template": "Hi",
+        "templateUrl": "package:other_package/template.html",
+        "styles": null,
+        "styleUrls": null,
+        "ngContentSelectors": null
+      }
+    }
+  }
+}