Second try: Fix resolution and canonicalization of typedefs and function types

runtime/vm/isolate_reload.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate_reload.h"
 
 #include "vm/become.h"
 #include "vm/bit_vector.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 1578 matching lines @@
         zone_(zone) {}
 
   virtual void VisitObject(RawObject* obj) {
     if (obj->IsPseudoObject()) {
       // Cannot even be wrapped in handles.
       return;
     }
     handle_ = obj;
     if (handle_.IsFunction()) {
       const Function& func = Function::Cast(handle_);
+      if (func.IsSignatureFunction()) {
+        return;
+      }
 
       // Switch to unoptimized code or the lazy compilation stub.
       func.SwitchToLazyCompiledUnoptimizedCode();
 
       // Grab the current code.
       code_ = func.CurrentCode();
       ASSERT(!code_.IsNull());
       const bool clear_code = IsFromDirtyLibrary(func);
       const bool stub_code = code_.IsStubCode();
 
@@ skipping 274 matching lines @@
         ASSERT(!super_cls.IsNull());
         super_cls.AddDirectSubclass(cls);
       }
     }
   }
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart