Remove guard page mechanism from promotion queue.

src/heap/heap-inl.h

 // 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.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 13 matching lines @@
   if (emergency_stack_ != NULL) {
     emergency_stack_->Add(Entry(target, size));
     return;
   }
 
   if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(rear_))) {
     NewSpacePage* rear_page =
         NewSpacePage::FromAddress(reinterpret_cast<Address>(rear_));
     DCHECK(!rear_page->prev_page()->is_anchor());
     rear_ = reinterpret_cast<intptr_t*>(rear_page->prev_page()->area_end());
-    ActivateGuardIfOnTheSamePage();
   }
 
-  if (guard_) {
-    DCHECK(GetHeadPage() ==
-           Page::FromAllocationTop(reinterpret_cast<Address>(limit_)));
-
-    if ((rear_ - 2) < limit_) {
-      RelocateQueueHead();
-      emergency_stack_->Add(Entry(target, size));
-      return;
-    }
+  if ((rear_ - 2) < limit_) {
+    RelocateQueueHead();
+    emergency_stack_->Add(Entry(target, size));
+    return;
   }
 
   *(--rear_) = reinterpret_cast<intptr_t>(target);
   *(--rear_) = size;
 // Assert no overflow into live objects.
 #ifdef DEBUG
   SemiSpace::AssertValidRange(target->GetIsolate()->heap()->new_space()->top(),
                               reinterpret_cast<Address>(rear_));
 #endif
 }
 
 
-void PromotionQueue::ActivateGuardIfOnTheSamePage() {
-  guard_ = guard_ ||
-           heap_->new_space()->active_space()->current_page()->address() ==
-               GetHeadPage()->address();
-}
-
-
 template <>
 bool inline Heap::IsOneByte(Vector<const char> str, int chars) {
   // TODO(dcarney): incorporate Latin-1 check when Latin-1 is supported?
   // ASCII only check.
   return chars == str.length();
 }
 
 
 template <>
 bool inline Heap::IsOneByte(String* str, int chars) {
@@ skipping 705 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_INL_H_