Debugger: use debug break slot to break on call.

test/mjsunit/debug-stepin-construct-call.js

+// Copyright 2015 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
+
+var break_count = 0;
+var exception = null;
+
+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);
+    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    break_count++;
+  } catch (e) {
+    exception = e;
+  }
+}
+
+var Debug = debug.Debug;
+Debug.setListener(listener);
+
+
+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);
+
+assertEquals(6, break_count);
+assertNull(exception);