stream: delete redundant code

In `Writable.prototype.end()`, `state.ending` is true after calling
`endWritable()` and it doesn't reset to false.

In `Writable.prototype.uncork()`, `state.finished` must be false
if `state.bufferedRequest` is true.

PR-URL: #18145
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>

Author: 陈刚

lib/_stream_writable.js

@@ -307,7 +307,6 @@ Writable.prototype.uncork = function() {
 
     if (!state.writing &&
         !state.corked &&
-        !state.finished &&
         !state.bufferProcessing &&
         state.bufferedRequest)
       clearBuffer(this, state);
@@ -579,7 +578,7 @@ Writable.prototype.end = function(chunk, encoding, cb) {
   }
 
   // ignore unnecessary end() calls.
-  if (!state.ending && !state.finished)
+  if (!state.ending)
     endWritable(this, state, cb);
 };