Report compile-time error when extending, mixing in or implementing a malformed type.

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 33907ca9cb27f6fd0902e0fd69e6315920ce096d..6bde7b8d7c60d9614ba73dbad8d0f9cd2fe9d74f 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -713,6 +713,30 @@ main() { F f = null; }"""]);
   static const MessageKind CANNOT_IMPLEMENT = const MessageKind(
       "Error: '#{type}' cannot be implemented.");
 
+  static const MessageKind CANNOT_EXTEND_MALFORMED = const MessageKind(
+      "Error: A class can't extend a malformed type.",
+      howToFix: "Try correcting the malformed type annotation or removing the "
+        "'extends' clause.",
+      examples: const ["""
+class A extends Malformed {}
+main() => new A();"""]);
+
+  static const MessageKind CANNOT_IMPLEMENT_MALFORMED = const MessageKind(
+      "Error: A class can't implement a malformed type.",
+      howToFix: "Try correcting the malformed type annotation or removing the "
+        "type from the 'implements' clause.",
+      examples: const ["""
+class A implements Malformed {}
+main() => new A();"""]);
+
+  static const MessageKind CANNOT_MIXIN_MALFORMED = const MessageKind(
+      "Error: A class can't mixin a malformed type.",
+      howToFix: "Try correcting the malformed type annotation or removing the "
+        "type from the 'with' clause.",
+      examples: const ["""
+class A extends Object with Malformed {}
+main() => new A();"""]);
+
   static const MessageKind CANNOT_MIXIN = const MessageKind(
       "Error: The type '#{type}' can't be mixed in.",
       howToFix: "Try removing '#{type}' from the 'with' clause.",