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

pkg/intl/test/message_extraction/verify_messages.dart

Index: pkg/intl/test/message_extraction/verify_messages.dart
diff --git a/pkg/intl/test/message_extraction/verify_messages.dart b/pkg/intl/test/message_extraction/verify_messages.dart
index f7be4912cdd16605680568d8aa03ed5894afacb2..f99848f36cd823d4633efbc86fd64905ca5b9664 100644
--- a/pkg/intl/test/message_extraction/verify_messages.dart
+++ b/pkg/intl/test/message_extraction/verify_messages.dart
@@ -66,6 +66,8 @@ verifyResult(ignored) {
   verify('2 Canadian dollars');
   verify('1 thing:');
   verify('2 things:');
+  verify('Hello World');
+  verify('Hello World');
 
   var fr_lines = expanded.skip(1).skipWhile(
       (line) => !line.contains('----')).toList();
@@ -128,6 +130,8 @@ verifyResult(ignored) {
   verify('2 dollars Canadiens');
   verify('1 chose:');
   verify('2 choses:');
+  verify('Bonjour tout le monde');
+  verify('Bonjour tout le monde');
 
   var de_lines = fr_lines.skip(1).skipWhile(
       (line) => !line.contains('----')).toList();
@@ -190,4 +194,6 @@ verifyResult(ignored) {
   verify('2 Kanadischen dollar');
   verify('eins:');
   verify('2 Dinge:');
+  verify('Hallo Welt');
+  verify('Hallo Welt');
 }