[undetectable] Really get comparisons of document.all right now.

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 341 matching lines @@
                                          Handle<Simd128Value>::cast(y)));
       } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
         }
       } else {
         return Just(false);
       }
     } else if (x->IsJSReceiver()) {
-      if (y->IsUndetectable()) {
+      if (y->IsJSReceiver()) {
+        return Just(x.is_identical_to(y));
+      } else if (y->IsUndetectable()) {
         return Just(x->IsUndetectable());
-      } else if (y->IsJSReceiver()) {
-        return Just(x.is_identical_to(y));
       } else if (y->IsBoolean()) {
         y = Oddball::ToNumber(Handle<Oddball>::cast(y));
       } else if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(x))
                       .ToHandle(&x)) {
         return Nothing<bool>();
       }
     } else {
       return Just(x->IsUndetectable() && y->IsUndetectable());
     }
   }
@@ skipping 19468 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8