[stubs] Use a single slot for context globals.

src/scopes.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/bootstrapper.h"
 #include "src/messages.h"
 #include "src/parser.h"
@@ skipping 1452 matching lines @@
 
 
 void Scope::AllocateDeclaredGlobal(Isolate* isolate, Variable* var) {
   DCHECK(var->scope() == this);
   DCHECK(!var->IsVariable(isolate->factory()->dot_result_string()) ||
          !var->IsStackLocal());
   if (var->IsUnallocated()) {
     if (var->IsStaticGlobalObjectProperty()) {
       DCHECK_EQ(-1, var->index());
       DCHECK(var->name()->IsString());
-      var->AllocateTo(VariableLocation::GLOBAL, num_heap_slots_);
+      var->AllocateTo(VariableLocation::GLOBAL, num_heap_slots_++);
       num_global_slots_++;
-      // Each global variable occupies two slots in the context: for reads
-      // and writes.
-      num_heap_slots_ += 2;
     } else {
       // There must be only DYNAMIC_GLOBAL in the script scope.
       DCHECK(!is_script_scope() || DYNAMIC_GLOBAL == var->mode());
     }
   }
 }
 
 
 void Scope::AllocateNonParameterLocalsAndDeclaredGlobals(Isolate* isolate) {
   // All variables that have no rewrite yet are non-parameter locals.
@@ skipping 105 matching lines @@
 int Scope::StackLocalCount() const {
   return num_stack_slots() -
       (function_ != NULL && function_->proxy()->var()->IsStackLocal() ? 1 : 0);
 }
 
 
 int Scope::ContextLocalCount() const {
   if (num_heap_slots() == 0) return 0;
   bool is_function_var_in_context =
       function_ != NULL && function_->proxy()->var()->IsContextSlot();
-  return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
-         2 * num_global_slots() - (is_function_var_in_context ? 1 : 0);
+  return num_heap_slots() - Context::MIN_CONTEXT_SLOTS - num_global_slots() -
+         (is_function_var_in_context ? 1 : 0);
 }
 
 
 int Scope::ContextGlobalCount() const { return num_global_slots(); }
+
 }  // namespace internal
 }  // namespace v8