VM: Enable collection of unoptimized code for optimized functions.

runtime/vm/visitor.h

Index: runtime/vm/visitor.h
===================================================================
--- runtime/vm/visitor.h	(revision 44959)
+++ runtime/vm/visitor.h	(working copy)
@@ -26,10 +26,12 @@
   virtual void VisitPointers(RawObject** first, RawObject** last) = 0;
 
   virtual bool visit_function_code() const { return true; }
-  virtual GrowableArray<RawFunction*>* skipped_code_functions() {
+  virtual GrowableArray<RawFunction*>* skipped_current_code_functions() {
     return NULL;
   }
-
+  virtual GrowableArray<RawFunction*>* skipped_unoptimized_code_functions() {
+    return NULL;
+  }
   // len argument is the number of pointers to visit starting from 'p'.
   void VisitPointers(RawObject** p, intptr_t len) {
     VisitPointers(p, (p + len - 1));