Fix issue with __proto__ when using ES6 object literals

src/ia32/full-codegen-ia32.cc

 // Copyright 2012 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/v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 2451 matching lines @@
     } else {
       __ push(Operand(esp, 0));  // prototype
     }
     EmitPropertyKey(property);
     VisitForStackValue(value);
     EmitSetHomeObjectIfNeeded(value, 2);
 
     switch (property->kind()) {
       case ObjectLiteral::Property::CONSTANT:
       case ObjectLiteral::Property::MATERIALIZED_LITERAL:
+      case ObjectLiteral::Property::PROTOTYPE:
+        UNREACHABLE();
       case ObjectLiteral::Property::COMPUTED:
-      case ObjectLiteral::Property::PROTOTYPE:
         __ CallRuntime(Runtime::kDefineClassMethod, 3);
         break;
 
       case ObjectLiteral::Property::GETTER:
         __ CallRuntime(Runtime::kDefineGetterPropertyUnchecked, 3);
         break;
 
       case ObjectLiteral::Property::SETTER:
         __ CallRuntime(Runtime::kDefineSetterPropertyUnchecked, 3);
         break;
-
-      default:
-        UNREACHABLE();
     }
   }
 
   // prototype
   __ CallRuntime(Runtime::kToFastProperties, 1);
 
   // constructor
   __ CallRuntime(Runtime::kToFastProperties, 1);
 }
 
@@ skipping 2739 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32