Reapply "Improve hashCode for closure objects" with fixes.

runtime/vm/dart_entry.cc

 // Copyright (c) 2011, 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/dart_entry.h"
 
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/debugger.h"
 #include "vm/object_store.h"
@@ skipping 491 matching lines @@
 
   const Array& args = Array::Handle(Array::New(kNumArguments));
   args.SetAt(0, left);
   args.SetAt(1, right);
   const Object& result =
       Object::Handle(DartEntry::InvokeFunction(function, args));
   ASSERT(result.IsInstance() || result.IsError());
   return result.raw();
 }
 
+// On success, returns a RawInstance.  On failure, a RawError.
+RawObject* DartLibraryCalls::IdentityHashCode(const Instance& object) {
+  const int kNumArguments = 1;
+  Thread* thread = Thread::Current();
+  Zone* zone = thread->zone();
+  const Library& libcore = Library::Handle(zone, Library::CoreLibrary());
+  ASSERT(!libcore.IsNull());
+  const Function& function = Function::Handle(
+      zone, libcore.LookupFunctionAllowPrivate(Symbols::identityHashCode()));
+  ASSERT(!function.IsNull());
+  const Array& args = Array::Handle(zone, Array::New(kNumArguments));
+  args.SetAt(0, object);
+  const Object& result =
+      Object::Handle(zone, DartEntry::InvokeFunction(function, args));
+  ASSERT(result.IsInstance() || result.IsError());
+  return result.raw();
+}
+
 RawObject* DartLibraryCalls::LookupHandler(Dart_Port port_id) {
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
   Function& function = Function::Handle(
       zone, thread->isolate()->object_store()->lookup_port_handler());
   const int kTypeArgsLen = 0;
   const int kNumArguments = 1;
   if (function.IsNull()) {
     Library& isolate_lib = Library::Handle(zone, Library::IsolateLibrary());
     ASSERT(!isolate_lib.IsNull());
@@ skipping 79 matching lines @@
   const Array& args = Array::Handle(Array::New(kNumArguments));
   args.SetAt(0, map);
   args.SetAt(1, key);
   args.SetAt(2, value);
   const Object& result =
       Object::Handle(DartEntry::InvokeFunction(function, args));
   return result.raw();
 }
 
 }  // namespace dart