X87: InstanceOfStub incorrectly interprets the hole as a prototype.

src/x87/code-stubs-x87.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.
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 1844 matching lines @@
   __ j(not_equal, &slow_case);
   __ LoadRoot(eax, Heap::kFalseValueRootIndex);
   __ ret(0);
 
   // Fast-case: The {function} must be a valid JSFunction.
   __ bind(&fast_case);
   __ JumpIfSmi(function, &slow_case);
   __ CmpObjectType(function, JS_FUNCTION_TYPE, function_map);
   __ j(not_equal, &slow_case);
 
+  // Go to the runtime if the function is not a constructor.
+  __ test_b(FieldOperand(function_map, Map::kBitFieldOffset),
+            static_cast<uint8_t>(1 << Map::kIsConstructor));
+  __ j(zero, &slow_case);
+
   // Ensure that {function} has an instance prototype.
   __ test_b(FieldOperand(function_map, Map::kBitFieldOffset),
             static_cast<uint8_t>(1 << Map::kHasNonInstancePrototype));
   __ j(not_zero, &slow_case);
 
   // Get the "prototype" (or initial map) of the {function}.
   __ mov(function_prototype,
          FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
   __ AssertNotSmi(function_prototype);
 
@@ skipping 3652 matching lines @@
                            return_value_operand, NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87