dart2js: Implement serialization of Capability for isolates.

sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart

Index: sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart b/sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart
index 9230bba9ff3e37e81bdacb6fde5929e2ab03e1d7..ba8f66b64d46bcd0614ed3c6a3abea8d3e278b79 100644
--- a/sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart
+++ b/sdk/lib/_internal/js_runtime/lib/isolate_serialization.dart
@@ -61,6 +61,7 @@ class _Serializer {
     if (x is _WorkerSendPort) return serializeWorkerSendPort(x);
 
     if (x is Closure) return serializeClosure(x);
+    if (x is CapabilityImpl) return serializeCapability(x);
 
     return serializeDartObject(x);
   }
@@ -204,6 +205,7 @@ class _Deserializer {
       case "raw sendport": return deserializeRawSendPort(x);
       case "js-object": return deserializeJSObject(x);
       case "function": return deserializeClosure(x);
+      case "capability": return deserializeCapability(x);
       case "dart": return deserializeDartObject(x);
       default: throw "couldn't deserialize: $x";
     }
@@ -345,6 +347,12 @@ class _Deserializer {
     return result;
   }
 
+  // ['capability', <id>].
+  Capability deserializeCapability(x) {
+    assert(x[0] == 'capability');
+    return new CapabilityImpl._internal(x[1]);
+  }
+
   // ['dart', <class-id>, <field-list>].
   deserializeDartObject(x) {
     assert(x[0] == 'dart');