Attempt no. 3 to fix Heap::IsHeapIterable and HeapIterator

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 2e2aa8e08fe732e71d5f0bff868e23ac32b208a1..66d17fbe6501fe46acfeffb81b1c70afdb155688 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -699,6 +699,10 @@ void Heap::GarbageCollectionEpilogue() {
   ReportStatisticsAfterGC();
 #endif  // DEBUG
   isolate_->debug()->AfterGarbageCollection();
+
+  // Remember the last top pointer so that we can later find out
+  // whether we allocated in new space since the last GC.
+  new_space_top_after_last_gc_ = new_space()->top();
 }
 
 
@@ -4321,14 +4325,15 @@ STRUCT_LIST(MAKE_CASE)
 
 bool Heap::IsHeapIterable() {
   return (!old_pointer_space()->was_swept_conservatively() &&
-          !old_data_space()->was_swept_conservatively());
+          !old_data_space()->was_swept_conservatively() &&
+          new_space_top_after_last_gc_ == new_space()->top());
 }
 
 
-void Heap::EnsureHeapIsIterable() {
+void Heap::MakeHeapIterable() {
   ASSERT(AllowHeapAllocation::IsAllowed());
   if (!IsHeapIterable()) {
-    CollectAllGarbage(kMakeHeapIterableMask, "Heap::EnsureHeapIsIterable");
+    CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   ASSERT(IsHeapIterable());
 }
@@ -5208,6 +5213,7 @@ bool Heap::SetUp() {
   if (!new_space_.SetUp(reserved_semispace_size_, max_semi_space_size_)) {
     return false;
   }
+  new_space_top_after_last_gc_ = new_space()->top();
 
   // Initialize old pointer space.
   old_pointer_space_ =
@@ -5731,7 +5737,9 @@ class UnreachableObjectsFilter : public HeapObjectsFilter {
 
 
 HeapIterator::HeapIterator(Heap* heap)
-    : heap_(heap),
+    : make_heap_iterable_helper_(heap),
+      no_heap_allocation_(),
+      heap_(heap),
       filtering_(HeapIterator::kNoFiltering),
       filter_(NULL) {
   Init();
@@ -5740,7 +5748,9 @@ HeapIterator::HeapIterator(Heap* heap)
 
 HeapIterator::HeapIterator(Heap* heap,
                            HeapIterator::HeapObjectsFiltering filtering)
-    : heap_(heap),
+    : make_heap_iterable_helper_(heap),
+      no_heap_allocation_(),
+      heap_(heap),
       filtering_(filtering),
       filter_(NULL) {
   Init();