test: add http_incoming's matchKnownFields test

https://github.com/nodejs/node/blob/master/lib/_http_incoming.js#L136
Coverage: https://coverage.nodejs.org/coverage-57f6a106fbc69a47/root/_http_incoming.js.html

PR-URL: nodejs#10811
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>

test/parallel/test-http-incoming-matchKnownFields.js

@@ -0,0 +1,90 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const IncomingMessage = require('http').IncomingMessage;
+
+function checkDest(field, result, value) {
+  const dest = {};
+
+  if (value) dest[field] = 'test';
+  const incomingMessage = new IncomingMessage(field);
+  // dest is changed by IncomingMessage._addHeaderLine
+  incomingMessage._addHeaderLine(field, value, dest);
+  assert.deepStrictEqual(dest, result);
+}
+
+checkDest('', {'': undefined});
+checkDest('Content-Type', {'content-type': undefined});
+checkDest('content-type', {'content-type': 'test'}, 'value');
+checkDest('User-Agent', {'user-agent': undefined});
+checkDest('user-agent', {'user-agent': 'test'}, 'value');
+checkDest('Referer', {referer: undefined});
+checkDest('referer', {referer: 'test'}, 'value');
+checkDest('Host', {host: undefined});
+checkDest('host', {host: 'test'}, 'value');
+checkDest('Authorization', {authorization: undefined}, undefined);
+checkDest('authorization', {authorization: 'test'}, 'value');
+checkDest('Proxy-Authorization', {'proxy-authorization': undefined});
+checkDest('proxy-authorization', {'proxy-authorization': 'test'}, 'value');
+checkDest('If-Modified-Since', {'if-modified-since': undefined});
+checkDest('if-modified-since', {'if-modified-since': 'test'}, 'value');
+checkDest('If-Unmodified-Since', {'if-unmodified-since': undefined});
+checkDest('if-unmodified-since', {'if-unmodified-since': 'test'}, 'value');
+checkDest('Form', {form: undefined});
+checkDest('form', {form: 'test, value'}, 'value');
+checkDest('Location', {location: undefined});
+checkDest('location', {location: 'test'}, 'value');
+checkDest('Max-Forwards', {'max-forwards': undefined});
+checkDest('max-forwards', {'max-forwards': 'test'}, 'value');
+checkDest('Retry-After', {'retry-after': undefined});
+checkDest('retry-after', {'retry-after': 'test'}, 'value');
+checkDest('Etag', {etag: undefined});
+checkDest('etag', {etag: 'test'}, 'value');
+checkDest('Last-Modified', {'last-modified': undefined});
+checkDest('last-modified', {'last-modified': 'test'}, 'value');
+checkDest('Server', {server: undefined});
+checkDest('server', {server: 'test'}, 'value');
+checkDest('Age', {age: undefined});
+checkDest('age', {age: 'test'}, 'value');
+checkDest('Expires', {expires: undefined});
+checkDest('expires', {expires: 'test'}, 'value');
+checkDest('Set-Cookie', {'set-cookie': [undefined]});
+checkDest('set-cookie', {'set-cookie': [undefined]});
+checkDest('Transfer-Encoding', {'transfer-encoding': undefined});
+checkDest('transfer-encoding', {'transfer-encoding': 'test, value'}, 'value');
+checkDest('Date', {date: undefined});
+checkDest('date', {date: 'test, value'}, 'value');
+checkDest('Connection', {connection: undefined});
+checkDest('connection', {connection: 'test, value'}, 'value');
+checkDest('Cache-Control', {'cache-control': undefined});
+checkDest('cache-control', {'cache-control': 'test, value'}, 'value');
+checkDest('Transfer-Encoding', {'transfer-encoding': undefined});
+checkDest('transfer-encoding', {'transfer-encoding': 'test, value'}, 'value');
+checkDest('Vary', {vary: undefined});
+checkDest('vary', {vary: 'test, value'}, 'value');
+checkDest('Content-Encoding', {'content-encoding': undefined}, undefined);
+checkDest('content-encoding', {'content-encoding': 'test, value'}, 'value');
+checkDest('Cookies', {cookies: undefined});
+checkDest('cookies', {cookies: 'test, value'}, 'value');
+checkDest('Origin', {origin: undefined});
+checkDest('origin', {origin: 'test, value'}, 'value');
+checkDest('Upgrade', {upgrade: undefined});
+checkDest('upgrade', {upgrade: 'test, value'}, 'value');
+checkDest('Expect', {expect: undefined});
+checkDest('expect', {expect: 'test, value'}, 'value');
+checkDest('If-Match', {'if-match': undefined});
+checkDest('if-match', {'if-match': 'test, value'}, 'value');
+checkDest('If-None-Match', {'if-none-match': undefined});
+checkDest('if-none-match', {'if-none-match': 'test, value'}, 'value');
+checkDest('Accept', {accept: undefined});
+checkDest('accept', {accept: 'test, value'}, 'value');
+checkDest('Accept-Encoding', {'accept-encoding': undefined});
+checkDest('accept-encoding', {'accept-encoding': 'test, value'}, 'value');
+checkDest('Accept-Language', {'accept-language': undefined});
+checkDest('accept-language', {'accept-language': 'test, value'}, 'value');
+checkDest('X-Forwarded-For', {'x-forwarded-for': undefined});
+checkDest('x-forwarded-for', {'x-forwarded-for': 'test, value'}, 'value');
+checkDest('X-Forwarded-Host', {'x-forwarded-host': undefined});
+checkDest('x-forwarded-host', {'x-forwarded-host': 'test, value'}, 'value');
+checkDest('X-Forwarded-Proto', {'x-forwarded-proto': undefined});
+checkDest('x-forwarded-proto', {'x-forwarded-proto': 'test, value'}, 'value');