Allow a single translation to be from multiple differently-named sources

pkg/intl/test/message_extraction/foo_messages_fr.dart

Index: pkg/intl/test/message_extraction/foo_messages_fr.dart
diff --git a/pkg/intl/test/message_extraction/foo_messages_fr.dart b/pkg/intl/test/message_extraction/foo_messages_fr.dart
index b57a2516f15af59b63ec532482602cfcd591157c..31c2eee968669313f9e5eebc51dd97bf343477c2 100644
--- a/pkg/intl/test/message_extraction/foo_messages_fr.dart
+++ b/pkg/intl/test/message_extraction/foo_messages_fr.dart
@@ -16,6 +16,8 @@ class MessageLookup extends MessageLookupByLibrary {
   get localeName => 'fr';
   static alwaysTranslated() => "Cette chaîne est toujours traduit";
 
+  static differentNameSameContents() => "Bonjour tout le monde";
+
   static escapable() => "Escapes: \n\r\f\b\t\v.";
 
   static leadingQuotes() => "\"Soi-disant\"";
@@ -52,6 +54,8 @@ class MessageLookup extends MessageLookupByLibrary {
 
   static plurals(num) => "${Intl.plural(num, zero: 'Est-ce que nulle est pluriel?', one: 'C\'est singulier', other: 'C\'est pluriel ($num).')}";
 
+  static sameContentsDifferentName() => "Bonjour tout le monde";
+
   static staticMessage() => "Cela vient d\'une méthode statique";
 
   static trickyInterpolation(s) => "L\'interpolation est délicate quand elle se termine une phrase comme ${s}.";
@@ -63,6 +67,7 @@ class MessageLookup extends MessageLookupByLibrary {
 
   final messages = const {
     "alwaysTranslated" : alwaysTranslated,
+    "differentNameSameContents" : differentNameSameContents,
     "escapable" : escapable,
     "leadingQuotes" : leadingQuotes,
     "message1" : message1,
@@ -81,6 +86,7 @@ class MessageLookup extends MessageLookupByLibrary {
     "outerSelect" : outerSelect,
     "pluralThatFailsParsing" : pluralThatFailsParsing,
     "plurals" : plurals,
+    "sameContentsDifferentName" : sameContentsDifferentName,
     "staticMessage" : staticMessage,
     "trickyInterpolation" : trickyInterpolation,
     "types" : types,