Store named parameters in sorted lists instead of using maps.

lib/binary/ast_to_binary.dart

Index: lib/binary/ast_to_binary.dart
diff --git a/lib/binary/ast_to_binary.dart b/lib/binary/ast_to_binary.dart
index 4e05ca45adedc678cf0fbd898219caf7502e6655..2a451ed7ba0dd0fa88cefaf1cedc635975acc961 100644
--- a/lib/binary/ast_to_binary.dart
+++ b/lib/binary/ast_to_binary.dart
@@ -893,15 +893,17 @@ class BinaryPrinter extends Visitor {
       writeNodeList(node.typeParameters);
       writeUInt30(node.requiredParameterCount);
       writeNodeList(node.positionalParameters);
-      writeList(node.namedParameters.keys.toList(), (String name) {
-        writeStringReference(name);
-        writeNode(node.namedParameters[name]);
-      });
+      writeNodeList(node.namedParameters);
       writeNode(node.returnType);
       _typeParameterIndexer.pop(node.typeParameters);
     }
   }
 
+  visitNamedType(NamedType node) {
+    writeStringReference(node.name);
+    writeNode(node.type);
+  }
+
   visitTypeParameterType(TypeParameterType node) {
     writeByte(Tag.TypeParameterType);
     writeUInt30(_typeParameterIndexer[node.parameter]);
@@ -1139,8 +1141,8 @@ class StringIndexer extends RecursiveVisitor<Null> {
     node.visitChildren(this);
   }
 
-  visitFunctionType(FunctionType node) {
-    node.namedParameters.keys.forEach(put);
+  visitNamedType(NamedType node) {
+    put(node.name);
     node.visitChildren(this);
   }