zlib: replace usage of internal stream state with public api

Refs: #445 PR-URL: #34884 Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Anna Henningsen <[email protected]>

Author: lundibundi

lib/zlib.js

@@ -349,17 +349,15 @@ const kFlushBuffers = [];
 }
 
 ZlibBase.prototype.flush=function(kind,callback){
-constws=this._writableState;
-
 if(typeofkind==='function'||(kind===undefined&&!callback)){
 callback=kind;
 kind=this._defaultFullFlushFlag;
 }
 
-if(ws.ended){
+if(this.writableFinished){
 if(callback)
 process.nextTick(callback);
-}elseif(ws.ending){
+}elseif(this.writableEnded){
 if(callback)
 this.once('end',callback);
 }else{
@@ -386,8 +384,7 @@ ZlibBase.prototype._transform = function(chunk, encoding, cb){
 }
 
 // For the last chunk, also apply `_finishFlushFlag`.
-constws=this._writableState;
-if((ws.ending||ws.ended)&&ws.length===chunk.byteLength){
+if(this.writableEnded&&this.writableLength===chunk.byteLength){
 flushFlag=maxFlush(flushFlag,this._finishFlushFlag);
 }
 processChunk(this,chunk,flushFlag,cb);