Make Dart_IdentityEqual live up to its sepc and not leak boxing implementation detail. (Reland r275…

runtime/vm/dart_api_impl_test.cc

 // Copyright (c) 2012, 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 "bin/builtin.h"
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
@@ skipping 183 matching lines @@
 
   // Same objects.
   EXPECT(Dart_IdentityEquals(five, five));
 
   // Equal objects.
   EXPECT(!Dart_IdentityEquals(five, five_again));
 
   // Different objects.
   EXPECT(!Dart_IdentityEquals(five, seven));
 
+  // Case where identical() is not the same as pointer equality.
+  Dart_Handle nan1 = Dart_NewDouble(NAN);
+  Dart_Handle nan2 = Dart_NewDouble(NAN);
+  EXPECT(Dart_IdentityEquals(nan1, nan2));
+
   // Non-instance objects.
   {
     Isolate* isolate = Isolate::Current();
     DARTSCOPE(isolate);
     Dart_Handle lib1 = Dart_LookupLibrary(dart_core);
     Dart_Handle lib2 = Dart_LookupLibrary(dart_mirrors);
 
     EXPECT(Dart_IdentityEquals(lib1, lib1));
     EXPECT(Dart_IdentityEquals(lib2, lib2));
     EXPECT(!Dart_IdentityEquals(lib1, lib2));
+
+    // Mix instance and non-instance.
+    EXPECT(!Dart_IdentityEquals(lib1, nan1));
+    EXPECT(!Dart_IdentityEquals(nan1, lib1));
   }
 }
 
 
 TEST_CASE(ObjectEquals) {
   bool equal = false;
   Dart_Handle five = NewString("5");
   Dart_Handle five_again = NewString("5");
   Dart_Handle seven = NewString("7");
 
@@ skipping 7086 matching lines @@
                                    NewString("main"),
                                    0,
                                    NULL);
   int64_t value = 0;
   result = Dart_IntegerToInt64(result, &value);
   EXPECT_VALID(result);
   EXPECT_EQ(8, value);
 }
 
 }  // namespace dart