Revert "Improvements to causal async stack traces"

tests/language/vm/causal_async_exception_stack2_test.dart

Index: tests/language/vm/causal_async_exception_stack2_test.dart
diff --git a/tests/language/vm/causal_async_exception_stack2_test.dart b/tests/language/vm/causal_async_exception_stack2_test.dart
deleted file mode 100644
index 18afd98a3811238abbe75859569a50a4306f818e..0000000000000000000000000000000000000000
--- a/tests/language/vm/causal_async_exception_stack2_test.dart
+++ /dev/null
@@ -1,98 +0,0 @@
-// 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.
-
-import 'package:unittest/unittest.dart';
-
-foo3() async => throw "foo";
-bar3() async => throw "bar";
-
-foo2() async => foo3();
-bar2() async => bar3();
-
-foo() async => foo2();
-bar() async => bar2();
-
-test1() async {
-  // test1 -> foo -> foo2 -> foo3
-  // test1 -> bar -> bar2 -> bar3
-  // These run interleaved, check their stack traces don't become mixed.
-  var a = foo();
-  var b = bar();
-
-  try {
-    await a;
-  } catch(e, st) {
-    // st has foo,2,3 and not bar,2,3.
-    expect(st.toString(), stringContainsInOrder([
-           'foo3',
-           '<asynchronous suspension>',
-           'foo2',
-           '<asynchronous suspension>',
-           'foo',
-           '<asynchronous suspension>',
-           'test1',
-           ]));
-    expect(st.toString().contains('bar'), isFalse);
-  }
-
-  try {
-    await b;
-  } catch(e, st) {
-    // st has bar,2,3 but not foo,2,3
-    expect(st.toString(), stringContainsInOrder([
-           'bar3',
-           '<asynchronous suspension>',
-           'bar2',
-           '<asynchronous suspension>',
-           'bar',
-           '<asynchronous suspension>',
-           'test1',
-           ]));
-    expect(st.toString().contains('foo'), isFalse);
-  }
-}
-
-test2() async {
-  // test2 -> foo -> foo2 -> foo3
-  // test2 -> bar -> bar2 -> bar3
-  // These run sequentially, check the former stack trace didn't get linked to
-  // from the latter stack trace.
-
-  try {
-    await foo();
-  } catch(e, st) {
-    // st has foo,2,3 but not bar,2,3
-    expect(st.toString(), stringContainsInOrder([
-           'foo3',
-           '<asynchronous suspension>',
-           'foo2',
-           '<asynchronous suspension>',
-           'foo',
-           '<asynchronous suspension>',
-           'test2',
-           ]));
-    expect(st.toString().contains('bar'), isFalse);
-  }
-
-  try {
-    await bar();
-  } catch(e, st) {
-    // st has bar,2,3 but not foo,2,3
-    expect(st.toString(), stringContainsInOrder([
-           'bar3',
-           '<asynchronous suspension>',
-           'bar2',
-           '<asynchronous suspension>',
-           'bar',
-           '<asynchronous suspension>',
-           'test2',
-           ]));
-    expect(st.toString().contains('foo'), isFalse);
-  }
-}
-
-main() async {
-  await test1();
-  await test2();
-}