http: simplify boolean checks

PR-URL: https://github.com/nodejs/node/pull/6533
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/_http_outgoing.js

@@ -239,7 +239,7 @@ function _storeHeader(firstLine, headers) {
     this.upgrading = true;
 
   // Date header
-  if (this.sendDate === true && state.sentDateHeader === false) {
+  if (this.sendDate && !state.sentDateHeader) {
     state.messageHeader += 'Date: ' + utcDate() + CRLF;
   }
 
@@ -255,8 +255,7 @@ function _storeHeader(firstLine, headers) {
   // of creating security liabilities, so suppress the zero chunk and force
   // the connection to close.
   var statusCode = this.statusCode;
-  if ((statusCode === 204 || statusCode === 304) &&
+  if ((statusCode === 204 || statusCode === 304) && this.chunkedEncoding) {
-      this.chunkedEncoding === true) {
     debug(statusCode + ' response should not use chunked encoding,' +
           ' closing connection.');
     this.chunkedEncoding = false;
@@ -267,7 +266,7 @@ function _storeHeader(firstLine, headers) {
   if (this._removedHeader.connection) {
     this._last = true;
     this.shouldKeepAlive = false;
-  } else if (state.sentConnectionHeader === false) {
+  } else if (!state.sentConnectionHeader) {
     var shouldSendKeepAlive = this.shouldKeepAlive &&
         (state.sentContentLengthHeader ||
          this.useChunkedEncodingByDefault ||
@@ -280,8 +279,7 @@ function _storeHeader(firstLine, headers) {
     }
   }
 
-  if (state.sentContentLengthHeader === false &&
+  if (!state.sentContentLengthHeader && !state.sentTransferEncodingHeader) {
-      state.sentTransferEncodingHeader === false) {
     if (!this._hasBody) {
       // Make sure we don't end the 0\r\n\r\n at the end of the message.
       this.chunkedEncoding = false;