Remove half of the checks for comparing two Obejcts

src/hydrogen.cc

 // Copyright 2013 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 9213 matching lines @@
     combined_type = left_type = right_type = handle(Type::Any(), isolate());
   }
 
   if (combined_type->Is(Type::Receiver())) {
     switch (op) {
       case Token::EQ:
       case Token::EQ_STRICT: {
         // Can we get away with map check and not instance type check?
         if (combined_type->IsClass()) {
           Handle<Map> map = combined_type->AsClass();
-          AddCheckMap(left, map);
-          AddCheckMap(right, map);
           HCompareObjectEqAndBranch* result =
-              New<HCompareObjectEqAndBranch>(left, right);
+              New<HCompareObjectEqAndBranch>(AddCheckMap(left, map),
+                                             AddCheckMap(right, map));
           if (FLAG_emit_opt_code_positions) {
             result->set_operand_position(zone(), 0, expr->left()->position());
             result->set_operand_position(zone(), 1, expr->right()->position());
           }
           return ast_context()->ReturnControl(result, expr->id());
         } else {
           BuildCheckHeapObject(left);
           Add<HCheckInstanceType>(left, HCheckInstanceType::IS_SPEC_OBJECT);
           BuildCheckHeapObject(right);
           Add<HCheckInstanceType>(right, HCheckInstanceType::IS_SPEC_OBJECT);
@@ skipping 1560 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal