Pass closure object as first implicit argument to closure functions.

runtime/vm/dart_entry.cc

Index: runtime/vm/dart_entry.cc
===================================================================
--- runtime/vm/dart_entry.cc	(revision 14694)
+++ runtime/vm/dart_entry.cc	(working copy)
@@ -99,6 +99,14 @@
       return error.raw();
     }
   }
+  // Set up arguments to include the closure as the first argument.
+  const int num_arguments = arguments.length() + 1;
+  GrowableArray<const Object*> args(num_arguments);
+  const Object& arg0 = Object::ZoneHandle(closure.raw());
+  args.Add(&arg0);
+  for (int i = 1; i < num_arguments; i++) {
+    args.Add(arguments[i - 1]);
+  }
   // Now Call the invoke stub which will invoke the closure.
   invokestub entrypoint = reinterpret_cast<invokestub>(
       StubCode::InvokeDartCodeEntryPoint());
@@ -107,8 +115,8 @@
   ASSERT(!code.IsNull());
   return entrypoint(
       code.EntryPoint(),
-      ArgumentsDescriptor(arguments.length(), optional_arguments_names),
-      arguments.data(),
+      ArgumentsDescriptor(num_arguments, optional_arguments_names),
+      args.data(),
       context);
 }