Fix capturing variables in optimized compilations

runtime/vm/parser.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_PARSER_H_
 #define VM_PARSER_H_
 
 #include "include/dart_api.h"
 
 #include "platform/assert.h"
@@ skipping 320 matching lines @@
   // Therefore, the statements being parsed may or may not belong to the body
   // of the current_function(); they may belong to nested functions.
   // innermost_function() is the function that is currently being parsed.
   // It is either the same as current_function(), or a lexically nested
   // function.
   // The function level of the current parsing scope reflects the function
   // nesting. The function level is zero while parsing the body of the
   // current_function(), but is greater than zero while parsing the body of
   // local functions nested in current_function().
 
+  // FunctionLevel is 0 when parsing code of current_function(), and denotes
+  // the relative nesting level when parsing a nested function.
+  int FunctionLevel() const;
+
   // The class being parsed.
   const Class& current_class() const;
   void set_current_class(const Class& value);
 
   // ParsedFunction accessor.
   ParsedFunction* parsed_function() const {
     return parsed_function_;
   }
 
   const Script& script() const { return script_; }
@@ skipping 630 matching lines @@
 
   intptr_t recursion_counter_;
   friend class RecursionChecker;
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 }  // namespace dart
 
 #endif  // VM_PARSER_H_