InstanceOfStub incorrectly interprets the hole as a prototype.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 3d359327fb4098c9aea58fa84267042a6d7e90fb..a5564d7ab9002b16cbf2db45c254bb7ab831b5f8 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -2137,6 +2137,11 @@ void InstanceOfStub::Generate(MacroAssembler* masm) {
   __ 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));