Count closures using the feedback vector cell map, specialize if count==1.

src/debug/liveedit.cc

Index: src/debug/liveedit.cc
diff --git a/src/debug/liveedit.cc b/src/debug/liveedit.cc
index 481197f91ecbeb99b96181fe3bae0abe6b2ded28..47199329076952244bce5905062aecb37694f230 100644
--- a/src/debug/liveedit.cc
+++ b/src/debug/liveedit.cc
@@ -761,7 +761,9 @@ class FeedbackVectorFixer {
 
     for (int i = 0; i < function_instances->length(); i++) {
       Handle<JSFunction> fun(JSFunction::cast(function_instances->get(i)));
-      fun->set_feedback_vector_cell(isolate->heap()->undefined_cell());
+      Handle<Cell> new_cell = isolate->factory()->NewManyClosuresCell(
+          isolate->factory()->undefined_value());
+      fun->set_feedback_vector_cell(*new_cell);
       // Only create feedback vectors if we already have the metadata.
       if (shared_info->is_compiled()) JSFunction::EnsureLiterals(fun);
     }