[js] Stub nqp::permit on the js backend

Author: pmurias

src/vm/js/Operations.nqp

@@ -1690,6 +1690,8 @@ class QAST::OperationsJS {
     add_simple_op('spawnprocasync', $T_OBJ, [$T_OBJ, $T_OBJ, $T_STR, $T_OBJ, $T_OBJ], :ctx, :side_effects);
     add_simple_op('killprocasync', $T_OBJ, [$T_OBJ, $T_INT], :side_effects);
 
+    add_simple_op('permit', $T_OBJ, [$T_OBJ, $T_INT, $T_INT], :side_effects);
+
     add_simple_op('semacquire', $T_OBJ, [$T_OBJ], :side_effects);
     add_simple_op('semtryacquire', $T_INT, [$T_OBJ], :side_effects);
     add_simple_op('semrelease', $T_OBJ, [$T_OBJ], :side_effects);

src/vm/js/nqp-runtime/io.js

@@ -524,3 +524,8 @@ op.spawnprocasync = function(ctx, queue, args, cwd, env, config) {
     config.content.get('done').$$call(ctx, null, result.status << 8);
   }
 };
+
+op.permit = function(handle, channel, permits) {
+  // TODO Implement permit handling properly
+  return handle;
+};