Delete standalone_2/io/process_exit_negative_test.dart.

I am trying to migrate all of the negative tests to something more
precise. As far as I can tell, this test stopped being useful with Dart
2.0. Now that all compilation errors are reported eagerly, the file
simply doesn't run at all. It's now just another test of an unresolved
identifier.

(This is a good example of *why* I want to get rid of negative tests.
This test silently went from a desired runtime failure to a compile-time
failure.)

Change-Id: Iec3cdd32a15612c0760119e92d618e3a5ba1f5ec
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/125555
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>

pkg/front_end/test/fasta/parser/parser.status

@@ -1966,7 +1966,6 @@ tests/lib_strong/mirrors/mirror_in_static_init_test: Fail
 tests/lib_strong/mirrors/other_declarations_location_test: Fail
 tests/lib_strong/mirrors/syntax_error_test: Fail
 tests/lib_strong/mirrors/typevariable_mirror_metadata_test: Fail
-tests/standalone/io/process_exit_negative_test: Fail
 tests/standalone/io/snapshot_fail_script: Fail
 tests/standalone/io/test_extension: Fail
 tests/standalone/io/test_relative_extension: Fail

tests/standalone/standalone_analyzer.status

@@ -4,5 +4,3 @@
 
 [ $compiler == dart2analyzer ]
 deferred_transitive_import_error_test: Skip # Contains intentional errors.
-io/process_exit_negative_test: Skip
-

tests/standalone_2/io/process_exit_negative_test.dart

@@ -1,21 +0,0 @@
-// Copyright (c) 2012, 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.
-//
-// Process test program to test that compilation errors in the process
-// exit handler are reported correctly.
-
-import "dart:io";
-import "process_test_util.dart";
-
-void main() {
-  var fp = Process.start(getProcessTestFileName(), const ["0", "0", "0", "0"]);
-  fp.then((p) {
-    p.exitCode.then((int s) {
-      print(a.toString()); // Should cause a compilation error here.
-    });
-    // Drain stdout and stderr.
-    p.stdout.listen((_) {});
-    p.stderr.listen((_) {});
-  });
-}

tests/standalone_2/standalone_2_analyzer.status

@@ -4,5 +4,3 @@
 
 [ $compiler == dart2analyzer ]
 deferred_transitive_import_error_test: Skip # Contains intentional errors.
-io/process_exit_negative_test: Skip
-