[Interpreter] Preserve source positions in peephole optimizer.

test/mjsunit/ignition/elided-instruction-no-ignition.js

-// Copyright 2016 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: --no-ignition --expose-debug-as debug
-
-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 {
-    print(event_data.sourceLineText());
-    var column = event_data.sourceColumn();
-    assertTrue(event_data.sourceLineText().indexOf(
-        `Break ${break_count++}. ${column}.`) > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn);
-  } catch (e) {
-    print(e + e.stack);
-    exception = e;
-  }
-};
-
-function f() {
-  var a = 1;                     // Break 2. 10.
-  return a;                      // Break 3. 2.
-}                                // Break 4. 0.
-
-Debug.setListener(listener);
-debugger;                        // Break 0. 0.
-f();                             // Break 1. 0.
-Debug.setListener(null);         // Break 5. 0.
-
-assertNull(exception);
-assertEquals(6, break_count);