Support typedefs in function signatures.

sdk/lib/_internal/lib/js_mirrors.dart

Index: sdk/lib/_internal/lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/lib/js_mirrors.dart b/sdk/lib/_internal/lib/js_mirrors.dart
index c54dc57cb3d3f28492c5eaa7170b8219b2b39a80..70f37ea7214b51fba374511f1ac68b3fc030490d 100644
--- a/sdk/lib/_internal/lib/js_mirrors.dart
+++ b/sdk/lib/_internal/lib/js_mirrors.dart
@@ -2693,6 +2693,8 @@ TypeMirror typeMirrorFromRuntimeTypeRepresentation(
   String representation;
   if (type == null) {
     return JsMirrorSystem._dynamicType;
+  } else if (type is Type) {
+    return reflectType(type);
   } else if (ownerClass == null) {
     representation = runtimeTypeToString(type);
   } else if (ownerClass.isOriginalDeclaration) {
@@ -2748,6 +2750,12 @@ TypeMirror typeMirrorFromRuntimeTypeRepresentation(
     return reflectClassByMangledName(
         getMangledTypeName(createRuntimeType(representation)));
   }
+  if (type != null && JS('Object|Null', '#.typedef', type) != null) {
+    return typeMirrorFromRuntimeTypeRepresentation(
+        owner, JS('Object', '#.typedef', type));
+  } else if (type != null && JS('Object|Null', '#.func', type) != null) {
+    return new JsFunctionTypeMirror(type, owner);
+  }
   return reflectClass(Function);
 }