Return correct helper for malformed type checks.

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 1085 matching lines @@
   }
 
   HType optimisticFieldType(Element element) {
     return fieldTypes.optimisticFieldType(element);
   }
 
   SourceString getCheckedModeHelper(DartType type) {
     Element element = type.element;
     bool nativeCheck =
           emitter.nativeEmitter.requiresNativeIsCheck(element);
-    if (type == compiler.types.voidType) {
+    if (type.isMalformed) {
+      // Check for malformed types first, because the type may be a list type
+      // with a malformed argument type.
+      return const SourceString('malformedTypeCheck');
+    } else if (type == compiler.types.voidType) {
       return const SourceString('voidTypeCheck');
     } else if (element == compiler.stringClass) {
       return const SourceString('stringTypeCheck');
     } else if (element == compiler.doubleClass) {
       return const SourceString('doubleTypeCheck');
     } else if (element == compiler.numClass) {
       return const SourceString('numTypeCheck');
     } else if (element == compiler.boolClass) {
       return const SourceString('boolTypeCheck');
     } else if (element == compiler.functionClass) {
       return const SourceString('functionTypeCheck');
     } else if (element == compiler.intClass) {
       return const SourceString('intTypeCheck');
     } 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');
       }
@@ skipping 46 matching lines @@
   }
 
   Element getSetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('setRuntimeTypeInfo'));
   }
 
   Element getGetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('getRuntimeTypeInfo'));
   }
 }