Change --hide-package-warnings to --show-package-warnings and add hint on suppress warnings.

sdk/lib/_internal/compiler/implementation/warnings.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 1730 matching lines @@
       "Variable '#{variableName}' is not shown to have type "
       "'#{shownType}' because '#{shownType}' is not a subtype of the "
       "known type '#{knownType}' of '#{variableName}'.");
 
   static const MessageKind NOT_MORE_SPECIFIC_SUGGESTION = const MessageKind(
       "Variable '#{variableName}' is not shown to have type "
       "'#{shownType}' because '#{shownType}' is not more specific than the "
       "known type '#{knownType}' of '#{variableName}'.",
       howToFix: "Try replacing '#{shownType}' with '#{shownTypeSuggestion}'.");
 
+  static const MessageKind HIDDEN_WARNINGS_HINTS = const MessageKind(
+      "#{warnings} warning(s) and #{hints} hint(s) suppressed in #{uri}.");
+
+  static const MessageKind HIDDEN_WARNINGS = const MessageKind(
+      "#{warnings} warning(s) suppressed in #{uri}.");
+
+  static const MessageKind HIDDEN_HINTS = const MessageKind(
+      "#{hints} hint(s) suppressed in #{uri}.");
+
   //////////////////////////////////////////////////////////////////////////////
   // Patch errors start.
   //////////////////////////////////////////////////////////////////////////////
 
   static const MessageKind PATCH_RETURN_TYPE_MISMATCH = const MessageKind(
       "Patch return type '#{patchReturnType}' does not match "
       "'#{originReturnType}' on origin method '#{methodName}'.");
 
   static const MessageKind PATCH_REQUIRED_PARAMETER_COUNT_MISMATCH =
       const MessageKind(
@@ skipping 130 matching lines @@
     return computeMessage();
   }
 
   bool operator==(other) {
     if (other is !Message) return false;
     return (kind == other.kind) && (toString() == other.toString());
   }
 
   int get hashCode => throw new UnsupportedError('Message.hashCode');
 }