Fix VM not accepting static methods for Isolate.spawn.

runtime/lib/isolate.cc

Index: runtime/lib/isolate.cc
diff --git a/runtime/lib/isolate.cc b/runtime/lib/isolate.cc
index 154ad01b042ac93b625d4ea7373a792dec59cf08..0f7da54201652a3f4787731a780d952e7e8f8023 100644
--- a/runtime/lib/isolate.cc
+++ b/runtime/lib/isolate.cc
@@ -215,30 +215,22 @@ static RawObject* Spawn(NativeArguments* arguments, IsolateSpawnState* state) {
 
 DEFINE_NATIVE_ENTRY(Isolate_spawnFunction, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(Instance, closure, arguments->NativeArgAt(0));
-  bool throw_exception = false;
-  Function& func = Function::Handle();
   if (closure.IsClosure()) {
+    Function& func = Function::Handle();
     func = Closure::function(closure);
-    const Class& cls = Class::Handle(func.Owner());
-    if (!func.IsClosureFunction() || !func.is_static() || !cls.IsTopLevel()) {
-      throw_exception = true;
-    }
-  } else {
-    throw_exception = true;
-  }
-  if (throw_exception) {
-    const String& msg = String::Handle(String::New(
-        "Isolate.spawn expects to be passed a top-level function"));
-    Exceptions::ThrowArgumentError(msg);
-  }
-
+    if (func.IsImplicitClosureFunction() && func.is_static()) {
 #if defined(DEBUG)
-  Context& ctx = Context::Handle();
-  ctx = Closure::context(closure);
-  ASSERT(ctx.num_variables() == 0);
+      Context& ctx = Context::Handle();
+      ctx = Closure::context(closure);
+      ASSERT(ctx.num_variables() == 0);
 #endif
-
-  return Spawn(arguments, new IsolateSpawnState(func));
+      return Spawn(arguments, new IsolateSpawnState(func));
+    }
+  }
+  const String& msg = String::Handle(String::New(
+      "Isolate.spawn expects to be passed a static or top-level function"));
+  Exceptions::ThrowArgumentError(msg);
+  return Object::null();
 }