[compiler] Remove broken support for undetectable strings.

src/full-codegen/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 4955 matching lines @@
 
   Factory* factory = isolate()->factory();
   if (String::Equals(check, factory->number_string())) {
     __ JumpIfSmi(eax, if_true);
     __ cmp(FieldOperand(eax, HeapObject::kMapOffset),
            isolate()->factory()->heap_number_map());
     Split(equal, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->string_string())) {
     __ JumpIfSmi(eax, if_false);
     __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, edx);
-    __ j(above_equal, if_false);
-    // Check for undetectable objects => false.
-    __ test_b(FieldOperand(edx, Map::kBitFieldOffset),
-              1 << Map::kIsUndetectable);
-    Split(zero, if_true, if_false, fall_through);
+    Split(below, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->symbol_string())) {
     __ JumpIfSmi(eax, if_false);
     __ CmpObjectType(eax, SYMBOL_TYPE, edx);
     Split(equal, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->boolean_string())) {
     __ cmp(eax, isolate()->factory()->true_value());
     __ j(equal, if_true);
     __ cmp(eax, isolate()->factory()->false_value());
     Split(equal, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->undefined_string())) {
@@ skipping 329 matching lines @@
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32