Add support for the new function-type syntax.

pkg/compiler/lib/src/resolution/signatures.dart

Index: pkg/compiler/lib/src/resolution/signatures.dart
diff --git a/pkg/compiler/lib/src/resolution/signatures.dart b/pkg/compiler/lib/src/resolution/signatures.dart
index faa927c43055f20dd33d9b8b67e191d6fc741392..f0704aa1fc2e58ee2cb063b8f95e88ebe5a3793a 100644
--- a/pkg/compiler/lib/src/resolution/signatures.dart
+++ b/pkg/compiler/lib/src/resolution/signatures.dart
@@ -302,6 +302,7 @@ class SignatureResolver extends MappingVisitor<FormalElementX> {
       FunctionTypedElement element,
       ResolutionRegistry registry,
       {MessageKind defaultValuesError,
+      bool isNewSyntax: false,

[Siggi Cherem (dart-lang), 2016/12/12 23:20:40]

while you are here, would you mind updating the dartdoc above. I would had
assumed that this was only used for function expressions and not for typedefs.

       bool createRealParameters: false,
       bool isFunctionExpression: false}) {
     DiagnosticReporter reporter = resolution.reporter;
@@ -418,7 +419,7 @@ class SignatureResolver extends MappingVisitor<FormalElementX> {
     List<Element> orderedOptionalParameters =
         visitor.optionalParameters.toList();
     if (visitor.optionalParametersAreNamed) {
-      // TODO(karlklose); replace when [visitor.optinalParameters] is a [List].
+      // TODO(karlklose); replace when [visitor.optionalParameters] is a [List].
       orderedOptionalParameters.sort((Element a, Element b) {
         return a.name.compareTo(b.name);
       });