Do not count invocations but usage of a function, i.e., increment a function's counter at IC calls …

runtime/vm/code_generator_ia32.h

Index: runtime/vm/code_generator_ia32.h
===================================================================
--- runtime/vm/code_generator_ia32.h	(revision 4578)
+++ runtime/vm/code_generator_ia32.h	(working copy)
@@ -123,10 +123,11 @@
     return false;
   }
 
-  virtual void CountBackwardLoop();
-
   void GenerateReturnEpilog(ReturnNode* node);
 
+  // Return true if the VM may optimize functions.
+  static bool CanOptimize();
+
  private:
   // TODO(srdjan): Remove the friendship once the two compilers are properly
   // structured.