[compiler] Remove broken support for undetectable strings.

src/full-codegen/arm64/full-codegen-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 4711 matching lines @@
   Factory* factory = isolate()->factory();
   if (String::Equals(check, factory->number_string())) {
     ASM_LOCATION("FullCodeGenerator::EmitLiteralCompareTypeof number_string");
     __ JumpIfSmi(x0, if_true);
     __ Ldr(x0, FieldMemOperand(x0, HeapObject::kMapOffset));
     __ CompareRoot(x0, Heap::kHeapNumberMapRootIndex);
     Split(eq, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->string_string())) {
     ASM_LOCATION("FullCodeGenerator::EmitLiteralCompareTypeof string_string");
     __ JumpIfSmi(x0, if_false);
-    // Check for undetectable objects => false.
-    __ JumpIfObjectType(x0, x0, x1, FIRST_NONSTRING_TYPE, if_false, ge);
-    __ Ldrb(x1, FieldMemOperand(x0, Map::kBitFieldOffset));
-    __ TestAndSplit(x1, 1 << Map::kIsUndetectable, if_true, if_false,
-                    fall_through);
+    __ CompareObjectType(x0, x0, x1, FIRST_NONSTRING_TYPE);
+    Split(lt, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->symbol_string())) {
     ASM_LOCATION("FullCodeGenerator::EmitLiteralCompareTypeof symbol_string");
     __ JumpIfSmi(x0, if_false);
     __ CompareObjectType(x0, x0, x1, SYMBOL_TYPE);
     Split(eq, if_true, if_false, fall_through);
   } else if (String::Equals(check, factory->boolean_string())) {
     ASM_LOCATION("FullCodeGenerator::EmitLiteralCompareTypeof boolean_string");
     __ JumpIfRoot(x0, Heap::kTrueValueRootIndex, if_true);
     __ CompareRoot(x0, Heap::kFalseValueRootIndex);
     Split(eq, if_true, if_false, fall_through);
@@ skipping 683 matching lines @@
   }
 
   return INTERRUPT;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64