Fix code flusher to process weak function links.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 0d2cc42402f4b3457b1d28340984069d452dbd7d..884db09e74a1424640ef822fe746efd3925d5c1c 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -1327,6 +1327,12 @@ void Heap::Scavenge() {
     }
   }
 
+  // Copy objects reachable from the code flushing candidates list.
+  MarkCompactCollector* collector = mark_compact_collector();
+  if (collector->is_code_flushing_enabled()) {
+    collector->code_flusher()->IteratePointersToFromSpace(&scavenge_visitor);
+  }
+
   // Scavenge object reachable from the native contexts list directly.
   scavenge_visitor.VisitPointer(BitCast<Object**>(&native_contexts_list_));
 
@@ -5542,6 +5548,7 @@ bool Heap::LookupSymbolIfExists(String* string, String** symbol) {
   return symbol_table()->LookupSymbolIfExists(string, symbol);
 }
 
+
 void Heap::ZapFromSpace() {
   NewSpacePageIterator it(new_space_.FromSpaceStart(),
                           new_space_.FromSpaceEnd());