Actually use canonicalized parameter and return types.

runtime/vm/class_finalizer.cc

Index: runtime/vm/class_finalizer.cc
diff --git a/runtime/vm/class_finalizer.cc b/runtime/vm/class_finalizer.cc
index 23c0d526fd8f58fd12d472a79fb74f01ad189f7e..78d45398c67d8697a216f487ec6da03eb3e9f10e 100644
--- a/runtime/vm/class_finalizer.cc
+++ b/runtime/vm/class_finalizer.cc
@@ -1165,7 +1165,7 @@ void ClassFinalizer::ResolveAndFinalizeSignature(const Class& cls,
       AbstractType::Handle(FinalizeType(cls, type, kCanonicalize));
   // The result type may be malformed or malbounded.
   if (type.raw() != finalized_type.raw()) {
-    function.set_result_type(type);
+    function.set_result_type(finalized_type);
   }
   // Resolve formal parameter types.
   const intptr_t num_parameters = function.NumParameters();
@@ -1174,7 +1174,7 @@ void ClassFinalizer::ResolveAndFinalizeSignature(const Class& cls,
     finalized_type = FinalizeType(cls, type, kCanonicalize);
     // The parameter type may be malformed or malbounded.
     if (type.raw() != finalized_type.raw()) {
-      function.SetParameterTypeAt(i, type);
+      function.SetParameterTypeAt(i, finalized_type);
     }
   }
 }