Filter out synthetic variables from with scopes

src/ast/scopeinfo.cc

 // Copyright 2011 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 <stdlib.h>
 
 #include "src/ast/context-slot-cache.h"
 #include "src/ast/scopes.h"
 #include "src/ast/variables.h"
 #include "src/bootstrapper.h"
@@ skipping 600 matching lines @@
 
 bool ScopeInfo::VariableIsSynthetic(String* name) {
   // There's currently no flag stored on the ScopeInfo to indicate that a
   // variable is a compiler-introduced temporary. However, to avoid conflict
   // with user declarations, the current temporaries like .generator_object and
   // .result start with a dot, so we can use that as a flag. It's a hack!
   return name->length() == 0 || name->Get(0) == '.' ||
          name->Equals(name->GetHeap()->this_string());
 }
 
+bool Scope::VariableIsSynthetic(const AstRawString* name) {

[adamk, 2016/09/19 20:01:25]

Yikes, I think this should be in scopes.cc. If you want to have them in the same
file, they should be in the same class, in which case I think putting them both
in Scope makes sense (as public static methods).

+  // There's currently no flag stored on the ScopeInfo to indicate that a
+  // variable is a compiler-introduced temporary. However, to avoid conflict
+  // with user declarations, the current temporaries like .generator_object and
+  // .result start with a dot, so we can use that as a flag. It's a hack!
+  return name->length() == 0 || name->FirstCharacter() == '.' ||
+         name->IsOneByteEqualTo("this");
+}
 
 int ScopeInfo::StackSlotIndex(String* name) {
   DCHECK(name->IsInternalizedString());
   if (length() > 0) {
     int first_slot_index = Smi::cast(get(StackLocalFirstSlotIndex()))->value();
     int start = StackLocalNamesIndex();
     int end = start + StackLocalCount();
     for (int i = start; i < end; ++i) {
       if (name == get(i)) {
         return i - start + first_slot_index;
@@ skipping 243 matching lines @@
   }
 
   Handle<ModuleInfo> result = isolate->factory()->NewModuleInfo();
   result->set(kSpecialExportsIndex, *special_exports);
   result->set(kRegularExportsIndex, *regular_exports);
   return result;
 }
 
 }  // namespace internal
 }  // namespace v8