Use maximum gzip compression (#1126)

* Use maximum gzip compression

* Revert extra changes

* Remove extra code used when testing brotli compression

* Remove extra space on unrelated changes

Author: pbolduc

tools/cdata.js

@@ -76,7 +76,7 @@ function writeHtmlGzipped(sourceFile, resultFile) {
     }
 
     html = adoptVersionAndRepo(html);
-    zlib.gzip(html, function (error, result) {
+    zlib.gzip(html, { level: zlib.constants.Z_BEST_COMPRESSION }, function (error, result) {
       if (error) {
         console.warn(error);
         throw error;