Re-apply r27739: Fix invocation_mirror_test.dart.

sdk/lib/_internal/compiler/implementation/types/type_graph_inferrer.dart

Index: sdk/lib/_internal/compiler/implementation/types/type_graph_inferrer.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/types/type_graph_inferrer.dart	(revision 27746)
+++ sdk/lib/_internal/compiler/implementation/types/type_graph_inferrer.dart	(working copy)
@@ -1370,11 +1370,16 @@
 
   TypeMask getReturnTypeOfElement(Element element) {
     if (compiler.disableTypeInference) return compiler.typesTask.dynamicType;
+    // Currently, closure calls return dynamic.
+    if (element is! FunctionElement) return compiler.typesTask.dynamicType;
     return inferrer.types.getInferredTypeOf(element).type;
   }
 
   TypeMask getTypeOfElement(Element element) {
     if (compiler.disableTypeInference) return compiler.typesTask.dynamicType;
+    // The inferrer stores the return type for a function, so we have to
+    // be careful to not return it here.
+    if (element is FunctionElement) return compiler.typesTask.functionType;
     return inferrer.types.getInferredTypeOf(element).type;
   }