Add FunctionEntity.asyncMarker and refactor SourceInformationStrategy to avoid ResolvedAst

pkg/compiler/lib/src/elements/elements.dart

Index: pkg/compiler/lib/src/elements/elements.dart
diff --git a/pkg/compiler/lib/src/elements/elements.dart b/pkg/compiler/lib/src/elements/elements.dart
index 9e3e5056928a74e32a0615cae3b67bccdb0b21b6..c1387a68ba9a8e1136c05e764744e9381f657b57 100644
--- a/pkg/compiler/lib/src/elements/elements.dart
+++ b/pkg/compiler/lib/src/elements/elements.dart
@@ -4,9 +4,6 @@
 
 library elements;
 
-import 'package:front_end/src/fasta/parser/async_modifier.dart'
-    show AsyncModifier;
-
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../constants/constructors.dart';
@@ -1342,58 +1339,6 @@ abstract class SetterElement extends AccessorElement {
   GetterElement get getter;
 }
 
-/// Enum for the synchronous/asynchronous function body modifiers.
-class AsyncMarker {
-  /// The default function body marker.
-  static const AsyncMarker SYNC = const AsyncMarker._(AsyncModifier.Sync);
-
-  /// The `sync*` function body marker.
-  static const AsyncMarker SYNC_STAR =
-      const AsyncMarker._(AsyncModifier.SyncStar, isYielding: true);
-
-  /// The `async` function body marker.
-  static const AsyncMarker ASYNC =
-      const AsyncMarker._(AsyncModifier.Async, isAsync: true);
-
-  /// The `async*` function body marker.
-  static const AsyncMarker ASYNC_STAR = const AsyncMarker._(
-      AsyncModifier.AsyncStar,
-      isAsync: true,
-      isYielding: true);
-
-  /// Is `true` if this marker defines the function body to have an
-  /// asynchronous result, that is, either a [Future] or a [Stream].
-  final bool isAsync;
-
-  /// Is `true` if this marker defines the function body to have a plural
-  /// result, that is, either an [Iterable] or a [Stream].
-  final bool isYielding;
-
-  final AsyncModifier asyncParserState;
-
-  const AsyncMarker._(this.asyncParserState,
-      {this.isAsync: false, this.isYielding: false});
-
-  String toString() {
-    return '${isAsync ? 'async' : 'sync'}${isYielding ? '*' : ''}';
-  }
-
-  /// Canonical list of marker values.
-  ///
-  /// Added to make [AsyncMarker] enum-like.
-  static const List<AsyncMarker> values = const <AsyncMarker>[
-    SYNC,
-    SYNC_STAR,
-    ASYNC,
-    ASYNC_STAR
-  ];
-
-  /// Index to this marker within [values].
-  ///
-  /// Added to make [AsyncMarker] enum-like.
-  int get index => values.indexOf(this);
-}
-
 /// A top level, static or instance function.
 abstract class MethodElement extends FunctionElement
     implements MemberElement, FunctionEntity {}