Refactor send and sendset unparsing.

tests/compiler/dart2js/unparser_test.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.
 
 #import('dart:uri');
 #import('parser_helper.dart');
 #import("../../../lib/compiler/compiler.dart");
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 
 testUnparse(String statement) {
@@ skipping 106 matching lines @@
 }
 
 testNativeMethods() {
   testUnparseMember('foo()native;');
   testUnparseMember('foo()native "bar";');
   testUnparseMember('foo()native "this.x = 41";');
 }
 
 testPrefixIncrements() {
   testUnparse(' ++i;');
-  testUnparse('++a[i];');
-  testUnparse('++a[++b[i]];');
+  testUnparse(' ++a[i];');
+  testUnparse(' ++a[ ++b[i]];');
 }
 
 testConstModifier() {
   testUnparse('foo([var a=const []]){}');
   testUnparse('foo([var a=const{}]){}');
   testUnparse('foo(){var a=const []; var b=const{};}');
   testUnparse('foo([var a=const [const{"a": const [1,2,3]}]]){}');
 }
 
 testSimpleFileUnparse() {
@@ skipping 280 matching lines @@
   testGetSet();
   testFactoryConstructor();
   testAbstractClass();
   testConflictSendsRename();
   testNoConflictSendsRename();
   testConflictLibraryClassRename();
   testDefaultClassWithArgs();
   testClassExtendsWithArgs();
   testStaticInvocation();
 }