perf(dart/transform) Restructure transform to independent phases

Update summary:
- Removes the need for resolution, gaining transform speed at the cost
  of some precision and ability to detect errors
- Generates type registrations in the package alongside their declarations
- Ensures that line numbers do not change in transformed user code

modules/angular2/src/transform/directive_linker/linker.dart

@@ -0,0 +1,56 @@
+library angular2.src.transform.directive_linker.linker;
+
+import 'dart:async';
+
+import 'package:angular2/src/transform/common/logging.dart';
+import 'package:angular2/src/transform/common/names.dart';
+import 'package:angular2/src/transform/common/ngdata.dart';
+import 'package:barback/barback.dart';
+import 'package:code_transformers/assets.dart';
+import 'package:dart_style/dart_style.dart';
+import 'package:path/path.dart' as path;
+
+Future<String> linkNgDeps(Transform transform, String code, String path) async {
+  var commentIdx = code.lastIndexOf('//');
+  if (commentIdx < 0) return code;
+
+  var ngData = new NgData.fromJson(code.substring(commentIdx + 2));
+
+  StringBuffer importBuf =
+      new StringBuffer(code.substring(0, ngData.importOffset));
+  StringBuffer declarationBuf = new StringBuffer(
+      code.substring(ngData.importOffset, ngData.registerOffset));
+  String tail = code.substring(ngData.registerOffset, commentIdx);
+
+  var ngDeps = await _processNgImports(transform, ngData.imports);
+
+  for (var i = 0; i < ngDeps.length; ++i) {
+    importBuf.write('import \'${ngDeps[i]}\' as i${i};');
+    declarationBuf.write('i${i}.${SETUP_METHOD_NAME}(${REFLECTOR_VAR_NAME});');
+  }
+
+  return '${importBuf}${declarationBuf}${tail}';
+}
+
+String _toDepsUri(String importUri) =>
+    '${path.withoutExtension(importUri)}${DEPS_EXTENSION}';
+
+bool _isNotDartImport(String importUri) {
+  return !importUri.startsWith('dart:');
+}
+
+Future<List<String>> _processNgImports(
+    Transform transform, List<String> imports) async {
+  var retVal = <String>[];
+
+  return Future
+      .wait(imports.where(_isNotDartImport).map(_toDepsUri).map((ngDepsUri) {
+    var importAsset = uriToAssetId(
+        transform.primaryInput.id, ngDepsUri, logger, null /* span */);
+    return transform.hasInput(importAsset).then((hasInput) {
+      if (hasInput) {
+        retVal.add(ngDepsUri);
+      }
+    });
+  })).then((_) => retVal);
+}

modules/angular2/src/transform/directive_linker/transformer.dart

@@ -0,0 +1,43 @@
+library angular2.src.transform.directive_linker.transformer;
+
+import 'dart:async';
+
+import 'package:angular2/src/transform/common/formatter.dart';
+import 'package:angular2/src/transform/common/logging.dart' as log;
+import 'package:angular2/src/transform/common/names.dart';
+import 'package:angular2/src/transform/common/options.dart';
+import 'package:barback/barback.dart';
+
+import 'linker.dart';
+
+/// Transformer responsible for processing .ngDeps.dart files created by
+/// [DirectiveProcessor] and ensuring that the generated calls to
+/// `setupReflection` call the necessary `setupReflection` method in all
+/// dependencies.
+class DirectiveLinker extends Transformer {
+  final TransformerOptions options;
+
+  DirectiveLinker(this.options);
+
+  @override
+  bool isPrimary(AssetId id) => id.path.endsWith(DEPS_EXTENSION);
+
+  @override
+  Future apply(Transform transform) async {
+    log.init(transform);
+
+    try {
+      var assetCode = await transform.primaryInput.readAsString();
+      var assetPath = transform.primaryInput.id.path;
+      var transformedCode = await linkNgDeps(transform, assetCode, assetPath);
+      var formattedCode = formatter.format(transformedCode, uri: assetPath);
+      transform.addOutput(
+          new Asset.fromString(transform.primaryInput.id, formattedCode));
+    } catch (ex, stackTrace) {
+      log.logger.error('Linking ng directives failed.\n'
+          'Exception: $ex\n'
+          'Stack Trace: $stackTrace');
+    }
+    return null;
+  }
+}