Delete dart_backend from compiler.

tests/compiler/dart2js/backend_dart/sexpr2_test.dart

-// Copyright (c) 2014, 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.
-
-/// Unittest test of the CPS ir generated by the dart2dart compiler.
-library dart_backend.sexpr2_test;
-
-import 'package:compiler/src/compiler.dart';
-import 'package:compiler/src/cps_ir/cps_ir_nodes.dart';
-import 'package:compiler/src/cps_ir/cps_ir_nodes_sexpr.dart';
-import 'package:compiler/src/elements/elements.dart';
-import 'package:expect/expect.dart';
-
-import '../../../../pkg/analyzer2dart/test/test_helper.dart';
-import '../../../../pkg/analyzer2dart/test/sexpr_data.dart';
-
-import 'test_helper.dart';
-
-main(List<String> args) {
-  performTests(TEST_DATA, asyncTester, runTest, args);
-}
-
-runTest(TestSpec result) {
-  return compilerFor(result.input).then((Compiler compiler) {
-    void checkOutput(String elementName,
-                     Element element,
-                     String expectedOutput) {
-      FunctionDefinition ir = compiler.irBuilder.getIr(element);
-      if (expectedOutput == null) {
-        Expect.isNull(ir, "\nInput:\n${result.input}\n"
-                          "No CPS IR expected for $element");
-      } else {
-        Expect.isNotNull(ir, "\nInput:\n${result.input}\n"
-                             "No CPS IR for $element");
-        expectedOutput = expectedOutput.trim();
-        String output = ir.accept(new SExpressionStringifier()).trim();
-        Expect.equals(expectedOutput, output,
-            "\nInput:\n${result.input}\n"
-            "Expected for '$elementName':\n$expectedOutput\n"
-            "Actual for '$elementName':\n$output\n");
-      }
-    }
-
-    if (result.output is String) {
-      checkOutput('main', compiler.mainFunction, result.output);
-    } else {
-      assert(result.output is Map<String, String>);
-      result.output.forEach((String elementName, String output) {
-        Element element;
-        if (elementName.contains('.')) {
-          ClassElement cls = compiler.mainApp.localLookup(
-              elementName.substring(0, elementName.indexOf('.')));
-          element = cls.localLookup(
-              elementName.substring(elementName.indexOf('.') + 1));
-        } else {
-          element = compiler.mainApp.localLookup(elementName);
-        }
-        checkOutput(elementName, element, output);
-      });
-    }
-  });
-}