Reland of [parsing] Fix maybe-assigned for loop variables.

src/ast/scopes.h

 // 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.
 
 #ifndef V8_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/base/hashmap.h"
 #include "src/globals.h"
@@ skipping 163 matching lines @@
                          InitializationFlag init_flag = kCreatedInitialized,
                          VariableKind kind = NORMAL_VARIABLE,
                          MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
 
   Variable* DeclareVariable(Declaration* declaration, VariableMode mode,
                             InitializationFlag init,
                             bool allow_harmony_restrictive_generators,
                             bool* sloppy_mode_block_scope_function_redefinition,
                             bool* ok);
 
+  // The return value is meaningful only if FLAG_preparser_scope_analysis is on.
   Variable* DeclareVariableName(const AstRawString* name, VariableMode mode);
 
   // Declarations list.
   ThreadedList<Declaration>* declarations() { return &decls_; }
 
   ThreadedList<Variable>* locals() { return &locals_; }
 
   // Create a new unresolved variable.
   VariableProxy* NewUnresolved(AstNodeFactory* factory,
                                const AstRawString* name,
@@ skipping 703 matching lines @@
   void AllocateModuleVariables();
 
  private:
   ModuleDescriptor* module_descriptor_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_