http2: remove unused using declarations node_http2

PR-URL: #20420
Reviewed-By: Anatoli Papirovski <[email protected]>
Reviewed-By: Tiancheng "Timothy" Gu <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>

Author: danbev

src/node_http2.h

@@ -16,7 +16,6 @@ namespace http2 {
 
 using v8::Array;
 using v8::Context;
-using v8::EscapableHandleScope;
 using v8::Isolate;
 using v8::MaybeLocal;