Track external allocated memory for weak persistent handles.

runtime/vm/heap.cc

Index: runtime/vm/heap.cc
===================================================================
--- runtime/vm/heap.cc	(revision 33235)
+++ runtime/vm/heap.cc	(working copy)
@@ -91,7 +91,22 @@
   return addr;
 }
 
+void Heap::AllocateExternal(intptr_t size, RawObject* ref) {
+  if (ref->IsHeapObject() && ref->IsNewObject()) {
+    new_space_->AllocateExternal(size);
+  } else {
+    old_space_->AllocateExternal(size);
+  }
+}
 
+void Heap::FreeExternal(intptr_t size, RawObject* ref) {
+  if (ref->IsHeapObject() && ref->IsNewObject()) {
+    new_space_->FreeExternal(size);
+  } else {
+    old_space_->FreeExternal(size);
+  }
+}
+
 bool Heap::Contains(uword addr) const {
   return new_space_->Contains(addr) ||
       old_space_->Contains(addr);
@@ -334,6 +349,10 @@
                          old_space_->CapacityInWords();
 }
 
+intptr_t Heap::ExternalAllocatedInWords(Space space) const {
+  return space == kNew ? new_space_->ExternalAllocatedInWords() :
+                         old_space_->ExternalAllocatedInWords();
+}
 
 int64_t Heap::GCTimeInMicros(Space space) const {
   if (space == kNew) {