Switch dart2js 'typedef name = mixinApplication' to 'class name = mixinApplication'.

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

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index 554a3bc81ec599759633fe2df8b40b75686cdb51..2a7ce78336d4ef022ca33e80e5f9ca9fdb1ca5b3 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -1031,6 +1031,18 @@ Error: '#{value}' is not a valid Symbol name because is not:
       "Error: No expression after 'throw'. "
       "Did you mean 'rethrow'?");
 
+  static const MessageKind DEPRECATED_TYPEDEF_MIXIN_SYNTAX = const MessageKind(
+      "Warning: 'typedef' not allowed here. ",
+      howToFix: "Try replacing 'typedef' with 'class'.",
+      examples: const [
+          """
+class B { }
+class M1 {  }
+typedef C = B with M1;  // Need to replace 'typedef' with 'class'.
+main() { new C(); }
+"""]
+);
+
   static const MessageKind MIRRORS_EXPECTED_STRING = const MessageKind(
       "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
       "and a 'String' value is expected.",