Introduce TypedefEntity

pkg/compiler/lib/src/kernel/element_map_impl.dart

Index: pkg/compiler/lib/src/kernel/element_map_impl.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map_impl.dart b/pkg/compiler/lib/src/kernel/element_map_impl.dart
index 12dc109b3899a1f3e0b39faea30edc6b0cee47a2..659729a21d702462729f5c45dcd1022bd24082ea 100644
--- a/pkg/compiler/lib/src/kernel/element_map_impl.dart
+++ b/pkg/compiler/lib/src/kernel/element_map_impl.dart
@@ -1265,6 +1265,12 @@ class KernelElementEnvironment implements ElementEnvironment {
     MemberData memberData = elementMap._memberData[member.memberIndex];
     return memberData.getMetadata(elementMap);
   }
+
+  @override
+  FunctionType getFunctionTypeOfTypedef(TypedefEntity typedef) {
+    // TODO(redemption): Support this.
+    throw new UnsupportedError('ElementEnvironment.getTypedefAlias');
+  }
 }
 
 /// Visitor that converts kernel dart types into [DartType].
@@ -1579,7 +1585,7 @@ class KernelClosedWorld extends ClosedWorldBase
       Iterable<ClassEntity> liveNativeClasses,
       Iterable<MemberEntity> liveInstanceMembers,
       Iterable<MemberEntity> assignedInstanceMembers,
-      Set<TypedefElement> allTypedefs,
+      Set<TypedefEntity> allTypedefs,
       Map<ClassEntity, Set<ClassEntity>> mixinUses,
       Map<ClassEntity, Set<ClassEntity>> typesImplementedBySubclasses,
       Map<ClassEntity, ClassHierarchyNode> classHierarchyNodes,