Remove guard page mechanism from promotion queue.

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index adb6e25bb710c581d8a6ae7b571b5eddc4732908..3b6a8033a291066905ee3807fcb8ca6266b3c2c2 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -31,18 +31,12 @@ void PromotionQueue::insert(HeapObject* target, int size) {
         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);
@@ -55,13 +49,6 @@ void PromotionQueue::insert(HeapObject* target, int size) {
 }
 
 
-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?