Clean up singleton implementation

pdfium.gyp

 # Copyright 2015 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'chromium_code': 1,
     'pdf_use_skia%': 0,
     'pdf_enable_v8%': 1,
     'pdf_enable_xfa%': 0, # Set to 1 by standalone.gypi in a standalone build.
@@ skipping 779 matching lines @@
             'fpdfsdk/javascript/Document.h',
             'fpdfsdk/javascript/Field.cpp',
             'fpdfsdk/javascript/Field.h',
             'fpdfsdk/javascript/Icon.cpp',
             'fpdfsdk/javascript/Icon.h',
             'fpdfsdk/javascript/JS_Define.h',
             'fpdfsdk/javascript/JS_EventHandler.cpp',
             'fpdfsdk/javascript/JS_EventHandler.h',
             'fpdfsdk/javascript/JS_GlobalData.cpp',
             'fpdfsdk/javascript/JS_GlobalData.h',
+            'fpdfsdk/javascript/JS_KeyValue.cpp',
+            'fpdfsdk/javascript/JS_KeyValue.h',
             'fpdfsdk/javascript/JS_Object.cpp',
             'fpdfsdk/javascript/JS_Object.h',
             'fpdfsdk/javascript/JS_Value.cpp',
             'fpdfsdk/javascript/JS_Value.h',
             'fpdfsdk/javascript/PublicMethods.cpp',
             'fpdfsdk/javascript/PublicMethods.h',
             'fpdfsdk/javascript/app.cpp',
             'fpdfsdk/javascript/app.cpp',
             'fpdfsdk/javascript/app.h',
             'fpdfsdk/javascript/color.cpp',
@@ skipping 254 matching lines @@
             'fpdfsdk/fpdfxfa/include/fpdfxfa_app.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_page.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_util.h',
           ],
         },
       ]
     }],
   ]
 }