Change dart:io to use Future for one-shot operations.

tests/standalone/io/process_exit_negative_test.dart

Index: tests/standalone/io/process_exit_negative_test.dart
diff --git a/tests/standalone/io/process_exit_negative_test.dart b/tests/standalone/io/process_exit_negative_test.dart
index 6e739780d0bd2156119e569b45f25bb8ce109476..c664ddfd49b9b1c08b6a849f6bef89ac816d74d3 100644
--- a/tests/standalone/io/process_exit_negative_test.dart
+++ b/tests/standalone/io/process_exit_negative_test.dart
@@ -9,8 +9,8 @@
 #source("process_test_util.dart");
 
 void main() {
-  Process p = new Process.start(getProcessTestFileName(),
-                                const ["0", "0", "0", "0"]);
+  InteractiveProcess p = Process.start(getProcessTestFileName(),
+                                       const ["0", "0", "0", "0"]);
   p.onExit = (int s) {
     print(a.toString());  // Should cause a compilation error here.
     p.close();