[compiler] Remove broken support for undetectable strings.

src/ia32/lithium-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/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 5475 matching lines @@
   Condition final_branch_condition = no_condition;
   if (String::Equals(type_name, factory()->number_string())) {
     __ JumpIfSmi(input, true_label, true_distance);
     __ cmp(FieldOperand(input, HeapObject::kMapOffset),
            factory()->heap_number_map());
     final_branch_condition = equal;
 
   } else if (String::Equals(type_name, factory()->string_string())) {
     __ JumpIfSmi(input, false_label, false_distance);
     __ CmpObjectType(input, FIRST_NONSTRING_TYPE, input);
-    __ j(above_equal, false_label, false_distance);
-    __ test_b(FieldOperand(input, Map::kBitFieldOffset),
-              1 << Map::kIsUndetectable);
-    final_branch_condition = zero;
+    final_branch_condition = below;
 
   } else if (String::Equals(type_name, factory()->symbol_string())) {
     __ JumpIfSmi(input, false_label, false_distance);
     __ CmpObjectType(input, SYMBOL_TYPE, input);
     final_branch_condition = equal;
 
   } else if (String::Equals(type_name, factory()->boolean_string())) {
     __ cmp(input, factory()->true_value());
     __ j(equal, true_label, true_distance);
     __ cmp(input, factory()->false_value());
@@ skipping 339 matching lines @@
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32