Check for uninitialized constant variables.

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 fe0c108f1e311faa46c1f8aca536736e06b98001..a35a6ad734bdfd24c18737bf80d3187c6277d17a 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -783,6 +783,15 @@ foo(t) {
 main() => foo(1);
 """]);
 
+  static const MessageKind CONST_WITHOUT_INITIALIZER = const MessageKind(
+      "Error: A constant variable must be initialized.",
+      howToFix: "Try adding an initializer or "
+                "removing the 'const' modifier.",
+      examples: const ["""
+void main() {
+  const c; // This constant variable must be initialized. 
+}"""]);
+
 
   static const MessageKind WRONG_NUMBER_OF_ARGUMENTS_FOR_ASSERT =
       const MessageKind(