Share test-source between full emitter and fast startup emitter dill tests.

tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart

 // Copyright (c) 2017, 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.
 
 // Helper to test compilation equivalence between source and .dill based
 // compilation.
 library dart2js.kernel.compile_from_dill_test_helper;
 
 import 'dart:async';
 import 'dart:io';
@@ skipping 11 matching lines @@
 import 'package:compiler/src/universe/world_builder.dart';
 import 'package:compiler/src/world.dart';
 import 'package:expect/expect.dart';
 import '../memory_compiler.dart';
 import '../equivalence/check_functions.dart';
 import '../equivalence/check_helpers.dart';
 import 'test_helpers.dart';
 
 import 'compiler_helper.dart';
 
+const SOURCE = const {
+  'main.dart': '''
+foo({named}) => 1;
+bar(a) => !a;
+class Class {
+  var field;
+  static var staticField;
+
+  Class();
+  Class.named(this.field);
+
+  method() {}
+}
+
+class SubClass extends Class {
+  method() {
+    super.method();
+  }  
+}
+main() {
+  foo();
+  bar(true);
+  [];
+  {};
+  new Object();
+  new Class.named('');
+  new SubClass().method();
+  Class.staticField;
+  var x = null;
+  var y1 = x == null;
+  var y2 = null == x;
+  var z1 = x?.toString();
+  var z2 = x ?? y1;
+  var z3 = x ??= y2;
+  var w = x == null ? null : x.toString();
+  for (int i = 0; i < 10; i++) {
+    if (i == 5) continue;
+    x = i;
+    if (i == 5) break;
+  }
+  int i = 0;
+  while (i < 10) {
+    if (i == 5) continue;
+    x = i;
+    if (i == 5) break;
+  }
+  for (var v in [3, 5]) {
+    if (v == 5) continue;
+    x = v;
+    if (v == 5) break;
+  }
+  print(x);
+  return x;
+}
+'''
+};
+
 enum ResultKind { crashes, errors, warnings, success, failure }
 
 Future<ResultKind> runTest(
     Uri entryPoint, Map<String, String> memorySourceFiles,
     {bool skipWarnings: false,
     bool skipErrors: false,
     bool verbose: false,
     List<String> options: const <String>[]}) async {
   enableDebugMode();
   EnumCreator.matchKernelRepresentationForTesting = true;
@@ skipping 109 matching lines @@
     }
     Map<String, BufferedOutputSink> map2 = collector2.outputMap[outputType];
     checkSets(map1.keys, map2.keys, 'output', equality);
     map1.forEach((String name, BufferedOutputSink output1) {
       BufferedOutputSink output2 = map2[name];
       Expect.stringEquals(output1.text, output2.text);
     });
   });
   return ResultKind.success;
 }