Fold IFWL_DateTimeCalendar into IFWL_MonthCalendar

BUILD.gn

 # Copyright 2016 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_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_common_config") {
   cflags = []
@@ skipping 1200 matching lines @@
       "xfa/fwl/core/ifwl_checkbox.h",
       "xfa/fwl/core/ifwl_combobox.cpp",
       "xfa/fwl/core/ifwl_combobox.h",
       "xfa/fwl/core/ifwl_comboboxproxy.cpp",
       "xfa/fwl/core/ifwl_comboboxproxy.h",
       "xfa/fwl/core/ifwl_comboedit.cpp",
       "xfa/fwl/core/ifwl_comboedit.h",
       "xfa/fwl/core/ifwl_combolist.cpp",
       "xfa/fwl/core/ifwl_combolist.h",
       "xfa/fwl/core/ifwl_dataprovider.h",
-      "xfa/fwl/core/ifwl_datetimecalendar.cpp",
-      "xfa/fwl/core/ifwl_datetimecalendar.h",
       "xfa/fwl/core/ifwl_datetimeedit.cpp",
       "xfa/fwl/core/ifwl_datetimeedit.h",
       "xfa/fwl/core/ifwl_datetimepicker.cpp",
       "xfa/fwl/core/ifwl_datetimepicker.h",
       "xfa/fwl/core/ifwl_edit.cpp",
       "xfa/fwl/core/ifwl_edit.h",
       "xfa/fwl/core/ifwl_form.cpp",
       "xfa/fwl/core/ifwl_form.h",
       "xfa/fwl/core/ifwl_formproxy.cpp",
       "xfa/fwl/core/ifwl_formproxy.h",
@@ skipping 539 matching lines @@
       "//samples",
     ]
   }
   group("fuzzers") {
     testonly = true
     deps = [
       "//testing/libfuzzer",
     ]
   }
 }