Minor cleanup of activation frame creation code. Get the code object while iterating the frames as …

vm/debugger.h

Index: vm/debugger.h
===================================================================
--- vm/debugger.h	(revision 18152)
+++ vm/debugger.h	(working copy)
@@ -119,7 +119,8 @@
 // on the call stack.
 class ActivationFrame : public ZoneAllocated {
  public:
-  explicit ActivationFrame(uword pc, uword fp, uword sp, const Context& ctx);
+  ActivationFrame(uword pc, uword fp, uword sp,
+                  const Code& code, const Context& ctx);
 
   uword pc() const { return pc_; }
   uword fp() const { return fp_; }
@@ -167,9 +168,8 @@
 
   // The anchor of the context chain for this function.
   const Context& ctx_;
-
-  Function& function_;
-  Code& code_;
+  const Code& code_;
+  const Function& function_;
   intptr_t token_pos_;
   intptr_t pc_desc_index_;
   intptr_t line_number_;