[debugger] flood function for stepping before calling it.

test/mjsunit/debug-step-into-json.js

Index: test/mjsunit/debug-step-into-json.js
diff --git a/test/mjsunit/debug-stepin-construct-call.js b/test/mjsunit/debug-step-into-json.js
similarity index 52%
copy from test/mjsunit/debug-stepin-construct-call.js
copy to test/mjsunit/debug-step-into-json.js
index 5e2145591fdb0bf6789fbc097ea7d5cb1ca5261e..b19850b6dbea5482011a181fbbd51454b203a3ae 100644
--- a/test/mjsunit/debug-stepin-construct-call.js
+++ b/test/mjsunit/debug-step-into-json.js
@@ -4,39 +4,32 @@
 
 // Flags: --expose-debug-as debug
 
-var break_count = 0;
+Debug = debug.Debug
+
 var exception = null;
+var break_count = 0;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
-    var source_line = exec_state.frame(0).sourceLineText();
-    print(source_line);
+    print(event_data.sourceLineText());
+    assertTrue(event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
     exec_state.prepareStep(Debug.StepAction.StepIn, 1);
-    break_count++;
   } catch (e) {
     exception = e;
   }
-}
-
-var Debug = debug.Debug;
-Debug.setListener(listener);
+};
 
+function toJsonCallback() {
+  return "x";                    // Break 2.
+}                                // Break 3.
+var o = {};
+o.toJSON = toJsonCallback;
 
-function f() {
-  this.x = 1;
-}
-
-function g() {
-  new f();
-}
-
-Debug.setBreakPoint(g, 6, Debug.BreakPositionAlignment.BreakPosition);
-print(Debug.showBreakPoints(g, undefined,
-      Debug.BreakPositionAlignment.BreakPosition));
-
-g();
-Debug.setListener(null);
+Debug.setListener(listener);
+debugger;                        // Break 0.
+var result = JSON.stringify(o);  // Break 1.
+Debug.setListener(null);         // Break 4.
 
-assertEquals(6, break_count);
+assertEquals('"x"', result);
 assertNull(exception);