fix analysis errors and warnings in the stocks example

examples/stocks/lib/i18n/stock_messages_en.dart

@@ -6,7 +6,7 @@
  */
 
 library messages_en;
-import 'package:intl/intl.dart';
+
 import 'package:intl/message_lookup_by_library.dart';
 
 final messages = new MessageLookup();
@@ -26,4 +26,4 @@ class MessageLookup extends MessageLookupByLibrary {
     "portfolio" : portfolio,
     "title" : title
   };
-}
\ No newline at end of file
+}

examples/stocks/lib/i18n/stock_messages_es.dart

@@ -6,7 +6,7 @@
  */
 
 library messages_es;
-import 'package:intl/intl.dart';
+
 import 'package:intl/message_lookup_by_library.dart';
 
 final messages = new MessageLookup();
@@ -26,4 +26,4 @@ class MessageLookup extends MessageLookupByLibrary {
     "portfolio" : portfolio,
     "title" : title
   };
-}
\ No newline at end of file
+}

packages/flutter/pubspec.yaml

@@ -25,6 +25,8 @@ dependencies:
 dev_dependencies:
   flutter_test:
     path: ../flutter_test
+  stocks:
+    path: ../../examples/stocks
 
 environment:
   sdk: '>=1.12.0 <2.0.0'