Follow-up to capturing instantiator

runtime/vm/scopes.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_SCOPES_H_
 #define VM_SCOPES_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/growable_array.h"
@@ skipping 266 matching lines @@
   SourceLabel* LookupInnermostLabel(Token::Kind jump_kind);
 
   // Lookup the label for the "innermost" catch block if one exists.
   SourceLabel* LookupInnermostCatchLabel();
 
   // Lookup scope of outer switch statement at same function level.
   // Returns NULL if this scope is not embedded in a switch.
   LocalScope* LookupSwitchScope();
 
   // Looks up variable in this scope and mark as captured if applicable.
-  // Finds the variable even if it is marked invisible.
-  void CaptureVariable(const String& name);
+  // Finds the variable even if it is marked invisible. Returns true if
+  // the variable was found, false if it was not found.
+  bool CaptureVariable(const String& name);
 
   // Look for unresolved forward references to labels in this scope.
   // If there are any, propagate the forward reference to the next
   // outer scope of a switch statement. If there is no outer switch
   // statement, return the first unresolved label found.
   SourceLabel* CheckUnresolvedLabels();
 
   // Accessing the variables in the scope.
   intptr_t num_variables() const { return variables_.length(); }
   LocalVariable* VariableAt(intptr_t index) const {
@@ skipping 65 matching lines @@
   intptr_t end_token_pos_;    // Token index of end of scope.
   GrowableArray<LocalVariable*> variables_;
   GrowableArray<SourceLabel*> labels_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCOPES_H_