[heap] Throw OOM upon failing to expand a PagedSpace above old gen limits.

The AlwaysAllocate scope make it impossible to enforce a DCHECK on the maximum
old generation sizes as e.g. large objects can still be allocated using this
scope. Returning false here results in OOM.

R=mstarzinger@chromium.org
BUG=chromium:525448
LOG=N

Review URL: https://codereview.chromium.org/1316183004

Cr-Commit-Position: refs/heads/master@{#30535}

src/heap/spaces.cc

@@ -1082,28 +1082,27 @@ Object* PagedSpace::FindObject(Address addr) {
 }
 
 
-bool PagedSpace::CanExpand() {
+bool PagedSpace::CanExpand(size_t size) {
   DCHECK(heap()->mark_compact_collector()->is_compacting() ||
          Capacity() <= heap()->MaxOldGenerationSize());
-  DCHECK(heap()->CommittedOldGenerationMemory() <=
-         heap()->MaxOldGenerationSize() +
-             PagedSpace::MaxEmergencyMemoryAllocated());
 
-  // Are we going to exceed capacity for this space?
-  if (!heap()->CanExpandOldGeneration(Page::kPageSize)) return false;
+  // Are we going to exceed capacity for this space? At this point we can be
+  // way over the maximum size because of AlwaysAllocate scopes and large
+  // objects.
+  if (!heap()->CanExpandOldGeneration(static_cast<int>(size))) return false;
 
   return true;
 }
 
 
 bool PagedSpace::Expand() {
-  if (!CanExpand()) return false;
-
   intptr_t size = AreaSize();
   if (snapshotable() && !HasPages()) {
     size = Snapshot::SizeOfFirstPage(heap()->isolate(), identity());
   }
 
+  if (!CanExpand(size)) return false;
+
   Page* p = heap()->isolate()->memory_allocator()->AllocatePage(size, this,
                                                                 executable());
   if (p == NULL) return false;

src/heap/spaces.h

@@ -1919,7 +1919,7 @@ class PagedSpace : public Space {
 
   void EvictEvacuationCandidatesFromFreeLists();
 
-  bool CanExpand();
+  bool CanExpand(size_t size);
 
   // Returns the number of total pages in this space.
   int CountTotalPages();