Add related types check to analyze_dart2js_test

pkg/compiler/lib/src/diagnostics/messages.dart

Index: pkg/compiler/lib/src/diagnostics/messages.dart
diff --git a/pkg/compiler/lib/src/diagnostics/messages.dart b/pkg/compiler/lib/src/diagnostics/messages.dart
index b812fd3347de67b9a77f3d1f3e1edeaa5faba1ca..b4246d65aca9b4ebfd1398f83cb92f00b68b8372 100644
--- a/pkg/compiler/lib/src/diagnostics/messages.dart
+++ b/pkg/compiler/lib/src/diagnostics/messages.dart
@@ -309,6 +309,7 @@ enum MessageKind {
   NATIVE_NOT_SUPPORTED,
   NO_BREAK_TARGET,
   NO_CATCH_NOR_FINALLY,
+  NO_COMMON_SUBTYPES,
   NO_CONTINUE_TARGET,
   NO_INSTANCE_AVAILABLE,
   NO_MATCHING_CONSTRUCTOR,
@@ -2894,6 +2895,10 @@ Please include the following information:
           howToFix:
             "Try replacing '#{shownType}' with '#{shownTypeSuggestion}'."),
 
+      MessageKind.NO_COMMON_SUBTYPES:
+        const MessageTemplate(MessageKind.NO_COMMON_SUBTYPES,
+           "Types '#{left}' and '#{right}' have no common subtypes."),
+
       MessageKind.HIDDEN_WARNINGS_HINTS:
         const MessageTemplate(MessageKind.HIDDEN_WARNINGS_HINTS,
           "#{warnings} warning(s) and #{hints} hint(s) suppressed in #{uri}."),