src: remove unused using in node_worker.cc

This commit removes unused using declarations in
src/node_worker.cc.

PR-URL: #32840
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: danbev

src/node_worker.cc

@@ -16,7 +16,6 @@ using node::kAllowedInEnvironment;
 using node::kDisallowedInEnvironment;
 using v8::Array;
 using v8::ArrayBuffer;
-using v8::BackingStore;
 using v8::Boolean;
 using v8::Context;
 using v8::Float64Array;
@@ -27,7 +26,6 @@ using v8::Integer;
 using v8::Isolate;
 using v8::Local;
 using v8::Locker;
-using v8::Maybe;
 using v8::MaybeLocal;
 using v8::Null;
 using v8::Number;