rev the engine

packages/flutter/pubspec.yaml

@@ -7,8 +7,8 @@ dependencies:
   collection: '>=1.1.3 <2.0.0'
   intl: '>=0.12.4+2 <0.13.0'
   material_design_icons: '>=0.0.3 <0.1.0'
-  sky_engine: 0.0.70
-  sky_services: 0.0.70
+  sky_engine: 0.0.71
+  sky_services: 0.0.71
   vector_math: '>=1.4.3 <2.0.0'
 
   # To pin the transitive dependency through mojo_sdk.

packages/updater/lib/pipe_to_file.dart

@@ -32,9 +32,8 @@ class PipeToFile {
 
   Future<int> drain() {
     Completer<int> completer = new Completer();
-    // TODO(mpcomplete): Is it legit to pass an async callback to subscribe?
-    _events.subscribe((List<int> event) async {
-      int signal = event[1];
+    _events.subscribe((int signal) {
+      (() async {
         if (MojoHandleSignals.isReadable(signal)) {
           int result = await _doRead();
           if (result != MojoResult.kOk) {
@@ -53,6 +52,7 @@ class PipeToFile {
         } else {
           throw 'Unexpected handle event: ${MojoHandleSignals.string(signal)}';
         }
+      })();
     });
     return completer.future;
   }