Revert of [es6] implement default parameters via desugaring

test/mjsunit/harmony/default-parameters-debug.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 --harmony-default-parameters
-
-// Get the Debug object exposed from the debug context global object.
-Debug = debug.Debug
-
-listenerComplete = false;
-breakPointCount = 0;
-
-function listener(event, exec_state, event_data, data) {
-  if (event == Debug.DebugEvent.Break) {
-    breakPointCount++;
-    if (breakPointCount == 1) {
-      // Break point in initializer for parameter `a`, invoked by
-      // initializer for parameter `b`
-      assertEquals('default', exec_state.frame(1).evaluate('mode').value());
-
-      // initializer for `b` can't refer to `b`
-      assertThrows(function() {
-        return exec_state.frame(1).evaluate('b').value();
-      }, ReferenceError);
-
-      assertThrows(function() {
-        return exec_state.frame(1).evaluate('c');
-      }, ReferenceError);
-    } else if (breakPointCount == 2) {
-      // Break point in IIFE initializer for parameter `c`
-      assertEquals('modeFn', exec_state.frame(1).evaluate('a.name').value());
-      assertEquals('default', exec_state.frame(1).evaluate('b').value());
-      assertThrows(function() {
-        return exec_state.frame(1).evaluate('c');
-      }, ReferenceError);
-    } else if (breakPointCount == 3) {
-      // Break point in function body --- `c` parameter is shadowed
-      assertEquals('modeFn', exec_state.frame(0).evaluate('a.name').value());
-      assertEquals('default', exec_state.frame(0).evaluate('b').value());
-      // TODO(caitp): fix scoping so that parameter `c` can be shadowed by vars
-      //assertEquals(true, exec_state.frame(0).evaluate('c').value());
-    }
-  }
-};
-
-// Add the debug event listener.
-Debug.setListener(listener);
-
-function f(a = function modeFn(mode) {
-                 debugger;
-                 return mode;
-               },
-           b = a("default"),
-           c = (function() {
-             debugger;
-           })()) {
-  // TODO(caitp): fix scoping so that parameter `c` can be shadowed by vars
-  //var c = true;
-  debugger;
-};
-
-f();
-
-// Make sure that the debug event listener vas invoked.
-assertEquals(3, breakPointCount);