Debugger: use debug break slots instead of ICs (except for calls).

test/mjsunit/es6/debug-stepnext-for.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --expose-debug-as debug --harmony
 
 Debug = debug.Debug;
 var break_count = 0
 var exception = null;
 var log = []
@@ skipping 88 matching lines @@
   "g16","g11","G4","g11","G4","g11","G4","g11",
   // For-of-var: next(), body, next(), body, ...
   "h16","H4","h16","H4","h16","H4","h16",
   // For-of: next(), body, next(), body, ...
   "i12","I4","i12","I4","i12","I4","i12",
   // For-of-let: next(), body, next(), ...
   "j16","J4","j16","J4","j16","J4","j16",
   // For-var: var decl, condition, body, next, condition, body, ...
   "k7","k20","K4","k23","k20","K4","k23","k20","K4","k23","k20",
   // For: init, condition, body, next, condition, body, ...
-  "l11","l16","L4","l19","l16","L4","l19","l16","L4","l19","l16",
+  "l7","l16","L4","l19","l16","L4","l19","l16","L4","l19","l16",
   // Exit.
   "y0","z0",
 ]
 print("expected:\n"+ JSON.stringify(expected));
 
 assertArrayEquals(expected, log);
 assertEquals(48, s);
 assertNull(exception);