Order the parameters of a function at the definition site.

lib/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
@@ skipping 140 matching lines @@
       js.Block body = new js.Block(<js.Statement>[]);
       if (codegen.setup != null) body.statements.add(codegen.setup);
       body.statements.add(codegen.body);
       js.Fun fun =
           buildJavaScriptFunction(work.element, codegen.newParameters, body);
       return prettyPrint(fun);
     });
   }
 
   Map<Element, String> getParameterNames(WorkItem work) {
+    // Make sure the map preserves insertion order, so that fetching
+    // the values will keep the order of parameters.
     Map<Element, String> parameterNames = new LinkedHashMap<Element, String>();
     FunctionElement function = work.element.implementation;
 
     // The dom/html libraries have inline JS code that reference
     // parameter names directly. Long-term such code will be rejected.
     // Now, just don't mangle the parameter name.
-    function.computeSignature(compiler).forEachParameter((Element element) {
+    FunctionSignature signature = function.computeSignature(compiler);
+    signature.orderedForEachParameter((Element element) {
       parameterNames[element] = function.isNative()
           ? element.name.slowToString()
           : JsNames.getValid('${element.name.slowToString()}');
     });
     return parameterNames;
   }
 }
 
 typedef void ElementAction(Element element);
 
@@ skipping 2816 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }