Rename blahHandler to onBlah throughout dart:io.

tests/standalone/src/DartStdIOPipeTest.dart

Index: tests/standalone/src/DartStdIOPipeTest.dart
diff --git a/tests/standalone/src/DartStdIOPipeTest.dart b/tests/standalone/src/DartStdIOPipeTest.dart
index 7dc9ba09db1bbc7c18d6aa23b4ebb70ab4c18f31..f07c1f5c5d6873b16d95c1929557229510ca284b 100644
--- a/tests/standalone/src/DartStdIOPipeTest.dart
+++ b/tests/standalone/src/DartStdIOPipeTest.dart
@@ -43,7 +43,7 @@ void test(String shellScript, String dartScript, String type) {
   Process process = new Process.start(shellScript, args);
 
   // Wait for the process to exit and then check result.
-  process.exitHandler = (exitCode) {
+  process.onExit = (exitCode) {
     Expect.equals(0, exitCode);
     process.close();
 
@@ -70,7 +70,7 @@ void test(String shellScript, String dartScript, String type) {
     dir.delete(true);
   };
 
-  process.errorHandler = (ProcessException error) {
+  process.onError = (ProcessException error) {
     Expect.fail(error.toString());
   };
 }