Reduce the number of captured variables in async code, by only capturing local

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 "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/allocation.h"
@@ skipping 309 matching lines @@
                         bool* found_captured_variables);
 
   // Creates variable info for the scope and all its nested scopes.
   // Must be called after AllocateVariables() has been called.
   RawLocalVarDescriptors* GetVarDescriptors(const Function& func);
 
   // Create a ContextScope object describing all captured variables referenced
   // from this scope and belonging to outer scopes.
   RawContextScope* PreserveOuterScope(int current_context_level) const;
 
-  // Recursively traverses all siblings and children and marks all variables as
-  // captured.
-  void RecursivelyCaptureAllVariables();
+  // Mark all local variables that are accessible from this scope up to
+  // top_scope (included) as captured.
+  void CaptureLocalVariables(LocalScope* top_scope);
 
   // Creates a LocalScope representing the outer scope of a local function to be
   // compiled. This outer scope contains the variables captured by the function
   // as specified by the given ContextScope, which was created during the
   // compilation of the enclosing function.
   static LocalScope* RestoreOuterScope(const ContextScope& context_scope);
 
   // Create a ContextScope object which will capture "this" for an implicit
   // closure object.
   static RawContextScope* CreateImplicitClosureScope(const Function& func);
@@ skipping 32 matching lines @@
   // List of names referenced in this scope and its children that
   // are not resolved to local variables.
   GrowableArray<NameReference*> referenced_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCOPES_H_