Revert "Improvements to causal async stack traces"

tests/language/vm/causal_async_exception_stack_test.dart

-// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// 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:unittest/unittest.dart';
 
 thrower() async {
   throw 'oops';
 }
 
 number() async {
   return 4;
 }
 
 generator() async* {
   yield await number();
   yield await thrower();
 }
 
 foo() async {
   await for (var i in generator()) {
     print(i);
   }
 }
 
 main() async {
-  // Test async and async*.
   try {
     await foo();
   } catch (e, st) {
     expect(st.toString(), stringContainsInOrder([
+        'thrower.<thrower_async_body>',
+        '<asynchronous suspension>',
         'thrower',
+        'generator.<generator_async_gen_body>',
         '<asynchronous suspension>',
         'generator',
+        'foo.<foo_async_body>',
         '<asynchronous suspension>',
-        'foo',
-        '<asynchronous suspension>',
-        'main',
         ]));
   }
-
-  inner() async {
-    deep() async {
-      await thrower();
-    }
-    await deep();
-  }
-
-  // Test inner functions.
-  try {
-    await inner();
-  } catch (e, st) {
-    expect(st.toString(), stringContainsInOrder([
-          'thrower',
-          '<asynchronous suspension>',
-          'main.inner.deep',
-          '<asynchronous suspension>',
-          'main.inner',
-          '<asynchronous suspension>',
-          'main',
-          '<asynchronous suspension>',
-          ]));
-  }
-
-  // Test for correct linkage.
-  try {
-    await thrower();
-  } catch(e, st) {
-    expect(st.toString(), stringContainsInOrder([
-           'thrower',
-           '<asynchronous suspension>',
-           'main',
-           ]));
-  }
 }