Fix hot reload test

pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart

Index: pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart
diff --git a/pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart b/pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart
index 45cd55bee410a50af4225ab41a0549ac40b39254..6b0d12bb059f064e709c6beece43c55b77f36f08 100644
--- a/pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart
+++ b/pkg/front_end/test/src/incremental/hot_reload_e2e_test.dart
@@ -53,7 +53,7 @@ main() {
   startProgram(int reloadCount) async {
     var vmArgs = [
       '--enable-vm-service=0', // Note: use 0 to avoid port collisions.
-      '--platform=${platformFile.toFilePath()}',
+      '--kernel-binaries=${sdkRoot.toFilePath()}',
       outputUri.toFilePath()
     ];
     vmArgs.add('$reloadCount');
@@ -98,7 +98,7 @@ main() {
   test('initial program is valid', () async {
     await startProgram(0);
     await programIsDone;
-    expect(await lines.skip(1).first, "part1 part2");
+    expect(await lines[1], "part1 part2");
   });
 
   test('reload after leaf library modification', () async {
@@ -156,7 +156,6 @@ main() {
 
 var dartVm = Uri.base.resolve(Platform.resolvedExecutable);
 var sdkRoot = dartVm.resolve("patched_sdk/");
-var platformFile = sdkRoot.resolve('platform.dill');
 
 Future<IncrementalKernelGenerator> createIncrementalCompiler(
     String entry, FileSystem fs) {
@@ -214,7 +213,12 @@ const sourceA = r'''
 import 'dart:async';
 import 'b.dart';
 
-void main(List<String> args) {
+void main(List<String> args) async {
+  // Note: this short delay is used to ensure the VM can initialize observatory
+  // first and we can obtain the port number as the first line in the output.
+  // If this becomes a source of flakiness, we can make the isolate pause on
+  // start and start the program via observatory instead.

[ahe, 2017/07/10 13:59:35]

Let's to that proactively.

[Siggi Cherem (dart-lang), 2017/07/10 19:31:11]

Done.

+  await new Future.delayed(new Duration(milliseconds: 100));
   var last = f();
   print(last);