Revert "Abort tracing in type inference in the presence of await."

pkg/compiler/lib/src/inferrer/type_graph_nodes.dart

Index: pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
diff --git a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
index 099a8113abc116bee4afb7b04538829b6a1a041f..6a9610dd3a04fe90f936cc68af39cbb1fd851451 100644
--- a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
+++ b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
@@ -1518,24 +1518,6 @@ abstract class TracedTypeInformation implements TypeInformation {
   }
 }
 
-class AwaitTypeInformation extends TypeInformation {
-  final ast.Node node;
-
-  AwaitTypeInformation(MemberTypeInformation context, this.node)
-      : super(context);
-
-  // TODO(22894): Compute a better type here.
-  TypeMask computeType(TypeGraphInferrerEngine inferrer) => safeType(inferrer);
-
-  String toString() => 'Await';
-
-  accept(TypeInformationVisitor visitor) {
-    return visitor.visitAwaitTypeInformation(this);
-  }
-
-  bool hasStableType(TypeGraphInferrerEngine inferrer) => true;
-}
-
 abstract class TypeInformationVisitor<T> {
   T visitNarrowTypeInformation(NarrowTypeInformation info);
   T visitPhiElementTypeInformation(PhiElementTypeInformation info);
@@ -1553,5 +1535,4 @@ abstract class TypeInformationVisitor<T> {
   T visitMemberTypeInformation(MemberTypeInformation info);
   T visitParameterTypeInformation(ParameterTypeInformation info);
   T visitClosureTypeInformation(ClosureTypeInformation info);
-  T visitAwaitTypeInformation(AwaitTypeInformation info);
 }