fix bug 56863. add plugins.properties to the list. r=blizzard sr=jst

xpfe/global/resources/locale/en-US/MANIFEST

@@ -15,3 +15,4 @@ accept2locale.properties
 languageNames.properties
 regionNames.properties
 commonDialogs.properties
+plugins.properties

xpfe/global/resources/locale/en-US/Makefile.in

@@ -49,6 +49,7 @@ CHROME_L10N = \
 		languageNames.properties \
 		regionNames.properties \
 		commonDialogs.properties \
+		plugins.properties \
 		$(NULL)
 
 include $(topsrcdir)/config/rules.mk

xpfe/global/resources/locale/en-US/makefile.win

@@ -44,6 +44,7 @@ CHROME_L10N = \
 	.\languageNames.properties \
 	.\regionNames.properties \
 	.\commonDialogs.properties \
+	.\plugins.properties \
 	$(NULL)
   
 include <$(DEPTH)\config\rules.mak>