[debugger] make step positions for for-of compatible with interpreter.

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

Index: test/mjsunit/es6/debug-stepnext-for.js
diff --git a/test/mjsunit/es6/debug-stepnext-for.js b/test/mjsunit/es6/debug-stepnext-for.js
index 9d5641a4a3c611d9711fdeb99d9613478c7451d9..d425a46b8445739a13cdd190e8e99985f553d9df 100644
--- a/test/mjsunit/es6/debug-stepnext-for.js
+++ b/test/mjsunit/es6/debug-stepnext-for.js
@@ -11,6 +11,8 @@ var log = []
 
 var s = 0;
 var a = [1, 2, 3];
+var b = [1, 2, 3, 4];
+var null_value = null;
 var i = 0;
 
 function f() {
@@ -18,11 +20,11 @@ function f() {
   debugger;                      // Break a
   var j;                         // Break b
 
-  for (var i in null) {          // Break c
+  for (var i in null_value) {    // Break c
     s += a[i];
   }
 
-  for (j in null) {              // Break d
+  for (j in null_value) {        // Break d
     s += a[j];
   }
 
@@ -46,7 +48,7 @@ function f() {
     s += j;                      // Break I
   }
 
-  for (let i of a) {             // Break j
+  for (let i  of  a) {           // Break j
     s += i;                      // Break J
   }
 
@@ -61,6 +63,11 @@ function f() {
   for (let i = 0; i < 3; i++) {  // Break m
     s += a[i];                   // Break M
   }
+
+  for (let i of a) {}            // Break n
+
+  [1, ...a]                      // Break o
+
 }                                // Break y
 
 function listener(event, exec_state, event_data, data) {
@@ -103,17 +110,21 @@ var expected = [
   // For-in-let: get enumerable, next, body, next,  ...
   "g16","g11","G4","g11","G4","g11","G4","g11",
   // For-of-var: [Symbol.iterator](), next(), body, next(), body, ...
-  "h16","h14","h15","H4","h15","H4","h15","H4","h15",
+  "h16","h13","H4","h13","H4","h13","H4","h13",
   // For-of: [Symbol.iterator](), next(), body, next(), body, ...
-  "i12","i10","i11","I4","i11","I4","i11","I4","i11",
+  "i12","i9","I4","i9","I4","i9","I4","i9",
   // For-of-let: [Symbol.iterator](), next(), body, next(), ...
-  "j16","j14","j15","J4","j15","J4","j15","J4","j15",
+  "j18","j14","J4","j14","J4","j14","J4","j14",
   // For-var: init, condition, body, next, condition, body, ...
   "k15","k20","K4","k26","k20","K4","k26","k20","K4","k26","k20",
   // For: init, condition, body, next, condition, body, ...
   "l7","l16","L4","l22","l16","L4","l22","l16","L4","l22","l16",
   // For-let: init, condition, body, next, condition, body, ...
   "m15","m20","M4","m26","m20","M4","m26","m20","M4","m26","m20",
+  // For-of, empty: [Symbol.iterator](), next() once
+  "n16", "n13",
+  // Spread: expression statement, spread
+  "o2", "o9",
   // Exit.
   "y0","z0",
 ]