Use JavaScript runtime semantics when constant folding.

lib/compiler/implementation/native_handler.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.
 
 #library('native');
 #import('dart:uri');
 #import('leg.dart');
 #import('elements/elements.dart');
 #import('js_backend/js_backend.dart');
 #import('scanner/scannerlib.dart');
@@ skipping 177 matching lines @@
       && element.isGetter()
       && nativeEmitter.toNativeName(element.getEnclosingClass()) == 'DOMType') {
     Element helper =
         compiler.findHelper(const SourceString('getTypeNameOf'));
     builder.pushInvokeHelper1(helper, builder.localsHandler.readThis());
     builder.close(new HReturn(builder.pop())).addSuccessor(builder.graph.exit);
   }
 
   HInstruction convertDartClosure(Element parameter, FunctionType type) {
     HInstruction local = builder.localsHandler.readLocal(parameter);
-    HInstruction arity = builder.graph.addConstantInt(type.computeArity());
+    Constant arityConstant =
+        builder.constantSystem.createInt(type.computeArity());
+    HInstruction arity = builder.graph.addConstant(arityConstant);
     // TODO(ngeoffray): For static methods, we could pass a method with a
     // defined arity.
     Element helper = builder.interceptors.getClosureConverter();
     builder.pushInvokeHelper2(helper, local, arity);
     HInstruction closure = builder.pop();
     return closure;
   }
 
   // Check which pattern this native method follows:
   // 1) foo() native; hasBody = false, isRedirecting = false
@@ skipping 120 matching lines @@
                                       String parameters) {
   buffer.add("  if (Object.getPrototypeOf(this).hasOwnProperty");
   buffer.add("('$methodName')) {\n");
   buffer.add("  $code");
   buffer.add("  } else {\n");
   buffer.add("    return Object.prototype.$methodName.call(this");
   buffer.add(parameters == '' ? '' : ', $parameters');
   buffer.add(");\n");
   buffer.add("  }\n");
 }