Remove saving/restoring of the context at function entry.

runtime/vm/scopes.cc

 // 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.
 
 #include "vm/scopes.h"
 
 #include "vm/object.h"
 #include "vm/stack_frame.h"
 #include "vm/symbols.h"
 
@@ skipping 307 matching lines @@
           ASSERT(var->owner()->context_level() >= 0);
           desc.info.scope_id = var->owner()->context_level();
         } else {
           desc.info.set_kind(RawLocalVarDescriptors::kStackVar);
           desc.info.scope_id = *scope_id;
         }
         desc.info.begin_pos = var->token_pos();
         desc.info.end_pos = var->owner()->end_token_pos();
         desc.info.set_index(var->index());
         vars->Add(desc);
-      } else if (var->name().raw() == Symbols::SavedEntryContextVar().raw()) {
-        // This is the local variable in which the function saves the
-        // caller's chain of closure contexts (caller's CTX register).
-        VarDesc desc;
-        desc.name = &var->name();
-        desc.info.set_kind(RawLocalVarDescriptors::kSavedEntryContext);
-        desc.info.scope_id = 0;
-        desc.info.begin_pos = 0;
-        desc.info.end_pos = 0;
-        desc.info.set_index(var->index());
-        vars->Add(desc);
       } else if (var->name().raw() == Symbols::CurrentContextVar().raw()) {
         // This is the local variable in which the function saves its
         // own context before calling a closure function.
         VarDesc desc;
         desc.name = &var->name();
         desc.info.set_kind(RawLocalVarDescriptors::kSavedCurrentContext);
         desc.info.scope_id = 0;
         desc.info.begin_pos = 0;
         desc.info.end_pos = 0;
         desc.info.set_index(var->index());
@@ skipping 323 matching lines @@
     return fixed_parameter_count - (index() - kParamEndSlotFromFp);
   } else {
     // Shift negative indexes so that the lowest one is 0 (they are still
     // non-positive).
     return fixed_parameter_count - (index() - kFirstLocalSlotFromFp);
   }
 }
 
 
 }  // namespace dart