Introduce .isMalformed

pkg/compiler/lib/src/elements/common.dart

Index: pkg/compiler/lib/src/elements/common.dart
diff --git a/pkg/compiler/lib/src/elements/common.dart b/pkg/compiler/lib/src/elements/common.dart
index f9c4e59201d82ebf3b347d49a57da339f3e362c6..bae94ef03790e825938b3d63797dfd2cc215bb09 100644
--- a/pkg/compiler/lib/src/elements/common.dart
+++ b/pkg/compiler/lib/src/elements/common.dart
@@ -76,12 +76,15 @@ abstract class ElementCommon implements Element {
   bool get isInitializingFormal => kind == ElementKind.INITIALIZING_FORMAL;
 
   @override
-  bool get isErroneous => kind == ElementKind.ERROR;
+  bool get isError => kind == ElementKind.ERROR;
 
   @override
   bool get isAmbiguous => kind == ElementKind.AMBIGUOUS;
 
   @override
+  bool get isMalformed => false;
+
+  @override
   bool get isWarnOnUse => kind == ElementKind.WARN_ON_USE;
 
   @override