[compiler] Remove broken support for undetectable strings.

src/code-stubs.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/code-stubs.h"
 
 #include <sstream>
 
 #include "src/bootstrapper.h"
 #include "src/cpu-profiler.h"
@@ skipping 995 matching lines @@
 
 
 bool ToBooleanStub::Types::NeedsMap() const {
   return Contains(ToBooleanStub::SPEC_OBJECT) ||
          Contains(ToBooleanStub::STRING) || Contains(ToBooleanStub::SYMBOL) ||
          Contains(ToBooleanStub::HEAP_NUMBER) ||
          Contains(ToBooleanStub::SIMD_VALUE);
 }
 
 
-bool ToBooleanStub::Types::CanBeUndetectable() const {
-  return Contains(ToBooleanStub::SPEC_OBJECT)
-      || Contains(ToBooleanStub::STRING);
-}
-
-
 void StubFailureTrampolineStub::GenerateAheadOfTime(Isolate* isolate) {
   StubFailureTrampolineStub stub1(isolate, NOT_JS_FUNCTION_STUB_MODE);
   StubFailureTrampolineStub stub2(isolate, JS_FUNCTION_STUB_MODE);
   stub1.GetCode();
   stub2.GetCode();
 }
 
 
 void ProfileEntryHookStub::EntryHookTrampoline(intptr_t function,
                                                intptr_t stack_pointer,
@@ skipping 44 matching lines @@
 
   if (type->Is(Type::UntaggedPointer())) {
     return Representation::External();
   }
 
   DCHECK(!type->Is(Type::Untagged()));
   return Representation::Tagged();
 }
 }  // namespace internal
 }  // namespace v8