Add StringLengthConstantExpression

tests/compiler/dart2js/semantic_visitor_test_send_data.dart

 // Copyright (c) 2015, 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.
 
 part of dart2js.semantics_visitor_test;
 
 const Map<String, List<Test>> SEND_TESTS = const {
   'Parameters': const [
     // Parameters
     const Test('m(o) => o;',
@@ skipping 3075 matching lines @@
         m() => const Class(true, 42);
         ''',
         const Visit(VisitKind.VISIT_CONST_CONSTRUCTOR_INVOKE,
             constant: 'const Class(true, 42)')),
     const Test(
         '''
         m() => const bool.fromEnvironment('foo');
         ''',
         const Visit(VisitKind.VISIT_BOOL_FROM_ENVIRONMENT_CONSTRUCTOR_INVOKE,
             constant:
-                'const bool.fromEnvironment("foo", defaultValue: false)')),
+                'const bool.fromEnvironment("foo")')),
     const Test(
         '''
         m() => const bool.fromEnvironment('foo', defaultValue: true);
         ''',
         const Visit(VisitKind.VISIT_BOOL_FROM_ENVIRONMENT_CONSTRUCTOR_INVOKE,
             constant: 'const bool.fromEnvironment("foo", defaultValue: true)')),
     const Test(
         '''
         m() => const int.fromEnvironment('foo');
         ''',
         const Visit(VisitKind.VISIT_INT_FROM_ENVIRONMENT_CONSTRUCTOR_INVOKE,
-            constant: 'const int.fromEnvironment("foo", defaultValue: null)')),
+            constant: 'const int.fromEnvironment("foo")')),
     const Test(
         '''
         m() => const String.fromEnvironment('foo');
         ''',
         const Visit(VisitKind.VISIT_STRING_FROM_ENVIRONMENT_CONSTRUCTOR_INVOKE,
             constant:
-                'const String.fromEnvironment("foo", defaultValue: null)')),
+                'const String.fromEnvironment("foo")')),
     const Test(
         '''
         class Class {
           Class(a, b);
         }
         m() => const Class(true, 42);
         ''',
         const Visit(VisitKind.ERROR_NON_CONSTANT_CONSTRUCTOR_INVOKE,
             element: 'generative_constructor(Class#)',
             arguments: '(true,42)',
@@ skipping 235 matching lines @@
         m() => new Class(true, 42);
         ''',
         const Visit(
             VisitKind.VISIT_UNRESOLVED_REDIRECTING_FACTORY_CONSTRUCTOR_INVOKE,
             element: 'function(Class#)',
             arguments: '(true,42)',
             type: 'Class',
             selector: 'CallStructure(arity=2)')),
   ],
 };