Ensure the debugger keeps a reference to code objects

runtime/vm/debugger.h

Index: runtime/vm/debugger.h
===================================================================
--- runtime/vm/debugger.h	(revision 31995)
+++ runtime/vm/debugger.h	(working copy)
@@ -74,10 +74,10 @@
 // function gets compiled as a regular function and as a closure.
 class CodeBreakpoint {
  public:
-  CodeBreakpoint(const Function& func, intptr_t pc_desc_index);
+  CodeBreakpoint(const Code& code, intptr_t pc_desc_index);
   ~CodeBreakpoint();
 
-  RawFunction* function() const { return function_; }
+  RawFunction* function() const;
   uword pc() const { return pc_; }
   intptr_t token_pos() const { return token_pos_; }
   bool IsInternal() const { return src_bpt_ == NULL; }
@@ -105,7 +105,7 @@
   void PatchCode();
   void RestoreCode();
 
-  RawFunction* function_;
+  RawCode* code_;
   intptr_t pc_desc_index_;
   intptr_t token_pos_;
   uword pc_;