Store named parameters in sorted lists instead of using maps.

lib/checks.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library kernel.checks;
 
 import 'ast.dart';
 
 void runSanityChecks(Program program) {
   CheckParentPointers.check(program);
   CheckReferences.check(program);
@@ skipping 57 matching lines @@
 
   visitClass(Class node) {
     currentClass = node;
     typeParameters.addAll(node.typeParameters);
     node.visitChildren(this);
     typeParameters.removeAll(node.typeParameters);
     currentClass = null;
   }
 
   visitFunctionNode(FunctionNode node) {
+    for (int i = 1; i < node.namedParameters.length; ++i) {
+      if (node.namedParameters[i - 1].compareTo(node.namedParameters[i]) >= 0) {
+        throw 'Named parameters are not sorted on function found in $context';
+      }
+    }
     typeParameters.addAll(node.typeParameters);
     node.visitChildren(this);
     typeParameters.removeAll(node.typeParameters);
   }
 
+  visitFunctionType(FunctionType node) {
+    for (int i = 1; i < node.namedParameters.length; ++i) {
+      if (node.namedParameters[i - 1].compareTo(node.namedParameters[i]) >= 0) {
+        throw 'Named parameters are not sorted on function type found in '
+            '$context';
+      }
+    }
+    node.visitChildren(this);
+  }
+
   @override
   defaultMemberReference(Member node) {
     if (!members.contains(node)) {
       throw 'Dangling reference to $node found in $context.\n'
           'Parent pointer is set to ${node.parent}';
     }
   }
 
   @override
   visitClassReference(Class node) {
@@ skipping 36 matching lines @@
         node.types.isEmpty) {
       ++emptyArguments;
     }
   }
 
   defaultNode(Node node) {
     ++size;
     node.visitChildren(this);
   }
 }