Fix flake in code_collection_test.

tests/standalone/io/code_collection_test.dart

 // Copyright (c) 2013, 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.
 
 // Dart test program testing code GC.
 
 import "package:expect/expect.dart";
 import "dart:async";
 import "dart:io";
 
@@ skipping 18 matching lines @@
   var ms = const Duration(milliseconds: 100);
   var t = new Timer.periodic(ms, (timer) {
     i++;
     // Calling bar will trigger GC without foo being on the stack. This way
     // the method can be collected.
     bar();
     if (i > 1) {
       timer.cancel();
       // foo is called again to make sure we can still run it even after
       // its code has been detached.
       var ret = foo(2);

[rmacnak, 2017/08/04 00:44:21]

GC after returning here may collect the second compilation of foo.

[zra, 2017/08/04 05:19:43]

Maybe add this as a comment.

[rmacnak, 2017/08/04 17:33:44]

Done.

     }
   });
 }
 
 List<String> packageOptions() {
   if (Platform.packageRoot != null) {
     return <String>['--package-root=${Platform.packageRoot}'];
   } else if (Platform.packageConfig != null) {
     return <String>['--packages=${Platform.packageConfig}'];
   } else {
@@ skipping 17 matching lines @@
       Platform.script.toFilePath(),
       "--run"
     ]);
     var pr = Process.runSync(Platform.executable, args);
 
     Expect.equals(0, pr.exitCode);
 
     // Code drops are logged with --log-code-drop. Look through stdout for the
     // message that foo's code was dropped.
     print(pr.stdout);
-    var count = 0;
+    bool saw_foo2 = false;
+    bool saw_detaching_foo = false;
+    bool saw_foo3 = false;
     pr.stdout.split("\n").forEach((line) {
       if (line.contains("foo=2")) {
-        Expect.equals(0, count);
-        count++;
+        Expect.isFalse(saw_foo2, "foo=2 ran twice");
+        saw_foo2 = true;
       }
       if (line.contains("Detaching code") && line.contains("foo")) {
-        Expect.equals(1, count);
-        count++;
+        Expect.isTrue(saw_foo2, "foo detached before running");
+        // May detach twice.
+        saw_detaching_foo = true;
       }
       if (line.contains("foo=3")) {
-        Expect.equals(2, count);
-        count++;
+        Expect.isFalse(saw_foo3, "foo=3 ran twice");
+        Expect.isTrue(saw_detaching_foo, "foo should have been collected");
+        saw_foo3 = true;
       }
     });
-    Expect.equals(3, count);
+
+    Expect.isTrue(saw_foo2, "Missing foo=2");
+    Expect.isTrue(saw_detaching_foo, "Missing code collection for foo");
+    Expect.isTrue(saw_foo3, "Missing foo=3");
   }
 }