fixup! src: simplify direct queries of env vars in C++ land

Author: joyeecheung

src/node_credentials.cc

@@ -24,13 +24,10 @@ namespace node {
 using v8::Array;
 using v8::Context;
 using v8::FunctionCallbackInfo;
-using v8::HandleScope;
 using v8::Isolate;
 using v8::Local;
 using v8::MaybeLocal;
 using v8::Object;
-using v8::String;
-using v8::TryCatch;
 using v8::Uint32;
 using v8::Value;
 

src/node_worker.cc

@@ -32,7 +32,6 @@ using v8::Isolate;
 using v8::Local;
 using v8::Locker;
 using v8::Maybe;
-using v8::MaybeLocal;
 using v8::Null;
 using v8::Number;
 using v8::Object;