Dart: Adds optional named arguments for creating bindings.

mojo/public/dart/src/proxy.dart

Index: mojo/public/dart/src/proxy.dart
diff --git a/mojo/public/dart/src/proxy.dart b/mojo/public/dart/src/proxy.dart
index f7c770f661eec75e183809e3249d5f7e2b0614f2..c275b3c1067a92432dd6c8bf452ad807690a932f 100644
--- a/mojo/public/dart/src/proxy.dart
+++ b/mojo/public/dart/src/proxy.dart
@@ -8,13 +8,15 @@ abstract class Proxy extends core.MojoEventStreamListener {
   Map<int, Completer> _completerMap;
   int _nextId = 0;
 
-  Proxy(core.MojoMessagePipeEndpoint endpoint) :
+  Proxy.fromEndpoint(core.MojoMessagePipeEndpoint endpoint,
+      {bool doListen: true, Function onClosed}) :
       _completerMap = {},
-      super(endpoint);
+      super.fromEndpoint(endpoint, doListen: doListen, onClosed: onClosed);
 
-  Proxy.fromHandle(core.MojoHandle handle) :
+  Proxy.fromHandle(core.MojoHandle handle,
+      {bool doListen: true, Function onClosed}) :
       _completerMap = {},
-      super.fromHandle(handle);
+      super.fromHandle(handle, doListen: doListen, onClosed: onClosed);
 
   Proxy.unbound() :
       _completerMap = {},