Emit a compile-time error when using default values in a redirecting factory.

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 4b2d1c7ac56e3100e157c502eb085f3e138dc851..fe1217679416383de8e343ccef32d28b1509cab9 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -644,7 +644,7 @@ main() {
 }"""]);
 
   static const MessageKind FUNCTION_TYPE_FORMAL_WITH_DEFAULT = const MessageKind(
-      "Error: A function type parameters can't specify a default value.",
+      "Error: A function type parameter can't specify a default value.",
       howToFix:
         "Try removing the default value.",
       examples: const ["""
@@ -659,6 +659,29 @@ main() {
   foo(1, a: 2);
 }"""]);
 
+  static const MessageKind REDIRECTING_FACTORY_WITH_DEFAULT = const MessageKind(
+      "Error: A parameter of a redirecting factory constructor can't specify a "
+      "default value.",
+      howToFix:
+        "Try removing the default value.",
+      examples: const ["""
+class A {
+  A([a]);
+  factory A.foo([a = 1]) = A;
+}
+
+main() {
+  new A.foo(1);
+}""", """
+class A {
+  A({a});
+  factory A.foo({a: 1}) = A;
+}
+
+main() {
+  new A.foo(a: 1);
+}"""]);
+
   static const MessageKind FORMAL_DECLARED_CONST = const MessageKind(
       "Error: A formal parameter can't be declared const.",
       howToFix: "Try removing 'const'.",