Add support for the new function-type syntax.

pkg/compiler/lib/src/diagnostics/messages.dart

Index: pkg/compiler/lib/src/diagnostics/messages.dart
diff --git a/pkg/compiler/lib/src/diagnostics/messages.dart b/pkg/compiler/lib/src/diagnostics/messages.dart
index d9785c64cca93be434ed7b0bd0a89e4293362269..3f445bea2159ec1578679388d4608f21902bffdf 100644
--- a/pkg/compiler/lib/src/diagnostics/messages.dart
+++ b/pkg/compiler/lib/src/diagnostics/messages.dart
@@ -275,6 +275,7 @@ enum MessageKind {
   INVALID_RECEIVER_IN_INITIALIZER,
   INVALID_SOURCE_FILE_LOCATION,
   INVALID_SYMBOL,
+  INVALID_INLINE_FUNCTION_TYPE,
   INVALID_SYNC_MODIFIER,
   INVALID_TYPE_VARIABLE_BOUND,
   INVALID_UNNAMED_CONSTRUCTOR_NAME,
@@ -3319,6 +3320,14 @@ Please include the following information:
           " require a preamble file located in:\n"
           "  <sdk>/lib/_internal/js_runtime/lib/preambles."),
 
+      MessageKind.INVALID_INLINE_FUNCTION_TYPE: const MessageTemplate(
+          MessageKind.INVALID_INLINE_FUNCTION_TYPE,
+          "Invalid inline function type.",
+          howToFix: "Change the inline function type to a prefixed "

[ahe, 2017/02/14 12:43:02]

"Change" -> "Try changing"

I think this message could use more work. I don't think most who see this
message will be familiar with what inline function type vs prefixed function
type means.

[floitsch, 2017/02/14 13:56:17]

Changed to:
Try changing the inline function type (as in 'int f()') to a prefixed function
type using the `Function` keyword (as in 'int Function() f').

Not sure that's better...

[ahe, 2017/02/15 11:50:17]

It's tricky. Ideally, we would say "Try this: '...'" where we have converted the
inline syntax to prefix syntax. But that's definitely future work.

+             "function type using the `Function` keyword.",
+          examples: const ["typedef F = Function(int f(String x))"],
+      ),
+
       MessageKind.INVALID_SYNC_MODIFIER: const MessageTemplate(
           MessageKind.INVALID_SYNC_MODIFIER, "Invalid modifier 'sync'.",
           howToFix: "Try replacing 'sync' with 'sync*'.",