Improve error for non-const implicit super constructor

pkg/compiler/lib/src/warnings.dart

Index: pkg/compiler/lib/src/warnings.dart
diff --git a/pkg/compiler/lib/src/warnings.dart b/pkg/compiler/lib/src/warnings.dart
index d7f1403a352bf965a0aee41014a9b19d55382ca2..dee59c6fbadca66a3ca867d78806d5401da1ea2a 100644
--- a/pkg/compiler/lib/src/warnings.dart
+++ b/pkg/compiler/lib/src/warnings.dart
@@ -481,6 +481,21 @@ main() => new C();"""]);
   static const MessageKind CONST_CALLS_NON_CONST = const MessageKind(
       "'const' constructor cannot call a non-const constructor.");
 
+  static const MessageKind CONST_CALLS_NON_CONST_FOR_IMPLICIT =
+      const MessageKind(
+          "'const' constructor cannot call implicit "
+          "super non-const constructor.",

[Johnni Winther, 2015/05/29 08:24:04]

The wording makes it sound like the constructor (and not the call) is implicit.

[Siggi Cherem (dart-lang), 2015/05/29 16:09:34]

Good point. Rephrased.

+          howToFix: "Try making the super constructor const",

[Johnni Winther, 2015/05/29 08:24:04]

'const' -> 'const.'

[Siggi Cherem (dart-lang), 2015/05/29 16:09:34]

Done.

+          examples: const ["""
+class C {
+  C(); // missing const
+}
+class D extends C {
+  final d;
+  const D(this.d);
+}
+main() => new D(0);"""]);
+
   static const MessageKind CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS =
       const MessageKind(
           "Can't declare constructor 'const' on class #{className} "