stream: simplify clearBuffer condition

Was doing some unecessary checks.

lib/_stream_writable.js

@@ -186,6 +186,7 @@ function WritableState(options, stream, isDuplex) {
 }
 
 ObjectDefineProperties(WritableState.prototype, {
+  // Backwards compat.
   writing: {
     get() {
       return !!this.writecb;
@@ -323,11 +324,7 @@ Writable.prototype.uncork = function() {
   if (state.corked) {
     state.corked--;
 
-    if (!state.writecb &&
-        !state.corked &&
-        !state.bufferProcessing &&
-        state.bufferedRequest)
-      clearBuffer(this, state);
+    clearBuffer(this, state);
   }
 };
 
@@ -432,13 +429,7 @@ function onwrite(stream, er) {
       onwriteError(stream, state, er, cb);
     }
   } else {
-    // Check if we're actually ready to finish, but don't emit yet
-    const finished = needFinish(state) || stream.destroyed;
-
-    if (!finished &&
-        !state.corked &&
-        !state.bufferProcessing &&
-        state.bufferedRequest) {
+    if (state.bufferedRequest) {
       clearBuffer(stream, state);
     }
 
@@ -503,6 +494,13 @@ function errorBuffer(state, err) {
 
 // If there's something in the buffer waiting, then process it
 function clearBuffer(stream, state) {
+  if (state.writecb ||
+      state.corked ||
+      state.bufferProcessing ||
+      !state.bufferedRequest) {
+    return;
+  }
+
   state.bufferProcessing = true;
   let entry = state.bufferedRequest;