Emit declarations for typedefs that are needed by reflection.

sdk/lib/_internal/compiler/implementation/world.dart

Index: sdk/lib/_internal/compiler/implementation/world.dart
diff --git a/sdk/lib/_internal/compiler/implementation/world.dart b/sdk/lib/_internal/compiler/implementation/world.dart
index b2e9c9c2ed38365f89045fea6af1d568d71850c0..9ecb9ea5f15ffd385f4aba2ac84c85beb9f3aee4 100644
--- a/sdk/lib/_internal/compiler/implementation/world.dart
+++ b/sdk/lib/_internal/compiler/implementation/world.dart
@@ -10,6 +10,8 @@ class World {
   final Set<Element> functionsCalledInLoop = new Set<Element>();
   final Map<Element, SideEffects> sideEffects = new Map<Element, SideEffects>();
 
+  final Set<TypedefElement> allTypedefs = new Set<TypedefElement>();
+
   final Map<ClassElement, Set<MixinApplicationElement>> mixinUses =
       new Map<ClassElement, Set<MixinApplicationElement>>();