Store JSGlobalProxy's identity hash directly on the proxy itself

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2730 matching lines @@
     CompileRun(
         "function cnst() { return 42; };\n"
         "Object.prototype.__defineGetter__('v8::IdentityHash', cnst);\n");
     Local<v8::Object> o1 = v8::Object::New(isolate);
     Local<v8::Object> o2 = v8::Object::New(isolate);
     CHECK_NE(o1->GetIdentityHash(), o2->GetIdentityHash());
   }
 }
 
 
+THREADED_TEST(GlobalProxyIdentityHash) {
+  LocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  v8::HandleScope scope(isolate);
+  Handle<Object> global_proxy = env->Global();
+  int hash1 = global_proxy->GetIdentityHash();
+  // Hash should be retained after being detached.
+  env->DetachGlobal();
+  int hash2 = global_proxy->GetIdentityHash();
+  CHECK_EQ(hash1, hash2);
+  {
+    // Re-attach global proxy to a new context, hash should stay the same.
+    LocalContext env2(NULL, Handle<ObjectTemplate>(), global_proxy);
+    int hash3 = global_proxy->GetIdentityHash();
+    CHECK_EQ(hash1, hash3);
+  }
+}
+
+
 THREADED_TEST(SymbolProperties) {
   i::FLAG_harmony_symbols = true;
 
   LocalContext env;
   v8::Isolate* isolate = env->GetIsolate();
   v8::HandleScope scope(isolate);
 
   v8::Local<v8::Object> obj = v8::Object::New(isolate);
   v8::Local<v8::Symbol> sym1 = v8::Symbol::New(isolate);
   v8::Local<v8::Symbol> sym2 =
@@ skipping 19725 matching lines @@
   v8::internal::FLAG_stack_size = 150;
   LocalContext current;
   v8::Isolate* isolate = current->GetIsolate();
   v8::HandleScope scope(isolate);
   V8::SetCaptureStackTraceForUncaughtExceptions(
       true, 10, v8::StackTrace::kDetailed);
   v8::TryCatch try_catch;
   CompileRun("(function f(x) { f(x+1); })(0)");
   CHECK(try_catch.HasCaught());
 }