MalformedType used for all invalid type annotations.

sdk/lib/_internal/compiler/implementation/js_backend/backend.dart

 // Copyright (c) 2012, 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 js_backend;
 
 typedef void Recompile(Element element);
 
 class ReturnInfo {
   HType returnType;
@@ skipping 1077 matching lines @@
     } else if (Elements.isNumberOrStringSupertype(element, compiler)) {
       return nativeCheck
           ? const SourceString('numberOrStringSuperNativeTypeCheck')
           : const SourceString('numberOrStringSuperTypeCheck');
     } else if (Elements.isStringOnlySupertype(element, compiler)) {
       return nativeCheck
           ? const SourceString('stringSuperNativeTypeCheck')
           : const SourceString('stringSuperTypeCheck');
     } else if (identical(element, compiler.listClass)) {
       return const SourceString('listTypeCheck');
+    } else if (type.isMalformed) {
+      return const SourceString('malformedTypeCheck');
     } else {
       if (Elements.isListSupertype(element, compiler)) {
         return nativeCheck
             ? const SourceString('listSuperNativeTypeCheck')
             : const SourceString('listSuperTypeCheck');
       } else {
         return nativeCheck
             ? const SourceString('callTypeCheck')
             : const SourceString('propertyTypeCheck');
       }
     }
   }
 
   void dumpInferredTypes() {
     print("Inferred argument types:");
     print("------------------------");
     argumentTypes.dump();
     print("");
     print("Inferred return types:");
     print("----------------------");
     dumpReturnTypes();
     print("");
     print("Inferred field types:");
     print("------------------------");
     fieldTypes.dump();
     print("");
   }
 }