[es6] Fix scoping for default parameters in arrow functions

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 # Because standalone V8 builds are not supported, assume this is part of a
@@ skipping 1092 matching lines @@
     "src/msan.h",
     "src/objects-debug.cc",
     "src/objects-inl.h",
     "src/objects-printer.cc",
     "src/objects.cc",
     "src/objects.h",
     "src/optimizing-compile-dispatcher.cc",
     "src/optimizing-compile-dispatcher.h",
     "src/ostreams.cc",
     "src/ostreams.h",
-    "src/pattern-rewriter.cc",
+    "src/parameter-initializer-rewriter.cc",
+    "src/parameter-initializer-rewriter.h",
     "src/parser.cc",
     "src/parser.h",
+    "src/pattern-rewriter.cc",
     "src/pending-compilation-error-handler.cc",
     "src/pending-compilation-error-handler.h",
     "src/preparse-data-format.h",
     "src/preparse-data.cc",
     "src/preparse-data.h",
     "src/preparser.cc",
     "src/preparser.h",
     "src/prettyprinter.cc",
     "src/prettyprinter.h",
     "src/profiler/allocation-tracker.cc",
@@ skipping 711 matching lines @@
     if (!is_component_build) {
       sources += [
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }