Clean up singleton implementation

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 562036ad23cf8a4d396f1a34279722fe44e4a22d..8e09f519d852691fb6fa34c696b7e57b850eb8bd 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -800,6 +800,8 @@ static_library("javascript") {
       "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",
@@ -1095,6 +1097,8 @@ if (pdf_enable_xfa) {
       "xfa/fwl/lightwidget/cfwl_widget.h",
       "xfa/fwl/lightwidget/cfwl_widgetproperties.cpp",
       "xfa/fwl/lightwidget/cfwl_widgetproperties.h",
+      "xfa/fwl/theme/cfwl_arrowdata.cpp",
+      "xfa/fwl/theme/cfwl_arrowdata.h",
       "xfa/fwl/theme/cfwl_barcodetp.cpp",
       "xfa/fwl/theme/cfwl_barcodetp.h",
       "xfa/fwl/theme/cfwl_carettp.cpp",