implement kernel -> ssa for simple binary expression

tests/compiler/dart2js/kernel/simple_function_test.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.
+
 import 'package:test/test.dart';
 
 import 'helper.dart' show check;
 
 main() {
   group('compile function that returns a value', () {
     test('constant int', () {
       return check('main() { return 1; }');
     });
 
@@ skipping 23 matching lines @@
       foo(x) {
         return x;
       }
 
       main() {
         foo(1);
       }''';
     return check(code, entry: 'foo');
   });
 }