Change the process API to be completely asynchronous.

tests/standalone/src/ProcessBrokenPipe.dart

Index: tests/standalone/src/ProcessBrokenPipe.dart
diff --git a/tests/standalone/src/ProcessBrokenPipe.dart b/tests/standalone/src/ProcessBrokenPipe.dart
index 3c6510fddea6a55c28cb31ceaaac8f18ec294a7e..942972b8a1debb70be5d32e840576260c8d2b08e 100644
--- a/tests/standalone/src/ProcessBrokenPipe.dart
+++ b/tests/standalone/src/ProcessBrokenPipe.dart
@@ -8,15 +8,12 @@
 
 main() {
   // Running dart without arguments makes it close right away.
-  Process process = new Process(getDartBinFileName(), []);
+  Process process = new Process.start(getDartBinFileName(), []);
 
   // Write to the stdin after the process is terminated to test
   // writing to a broken pipe.
-  OutputStream output = process.stdin;
   process.exitHandler = (code) {
-    Expect.isFalse(output.write([0]));
+    Expect.isFalse(process.stdin.write([0]));
     process.close();
   };
-
-  process.start();
 }