use Date.now() instead of new Date().getTime()

This is documented to be more performant.

The substitution was made on frontend code, too (i.e., the one in /static),
because Date.now() is supported since IE 9, and we are life supporting only
IE 11.

Commands:
  find . -name *.js | xargs sed --in-place "s/new Date().getTime()/Date.now()/g"
  find . -name *.js | xargs sed --in-place "s/(new Date()).getTime()/Date.now()/g"

Not done on jQuery.

src/node/db/API.js

@@ -522,7 +522,7 @@ exports.appendChatMessage = function(padID, text, authorID, time, callback)
   if(time === undefined || !is_int(time))
   {
     // set time to current timestamp
-    time = new Date().getTime();
+    time = Date.now();
   }
 
   var padMessage = require("ep_etherpad-lite/node/handler/PadMessageHandler.js");

src/node/db/AuthorManager.js

@@ -110,7 +110,7 @@ function mapAuthorWithDBKey (mapperkey, mapper, callback)
 
     //there is a author with this mapper
     //update the timestamp of this author
-    db.setSub("globalAuthor:" + author, ["timestamp"], new Date().getTime());
+    db.setSub("globalAuthor:" + author, ["timestamp"], Date.now());
 
     //return the author
     callback(null, {authorID: author});
@@ -127,7 +127,7 @@ exports.createAuthor = function(name, callback)
   var author = "a." + randomString(16);
 
   //create the globalAuthors db entry
-  var authorObj = {"colorId" : Math.floor(Math.random()*(exports.getColorPalette().length)), "name": name, "timestamp": new Date().getTime()};
+  var authorObj = {"colorId" : Math.floor(Math.random()*(exports.getColorPalette().length)), "name": name, "timestamp": Date.now()};
 
   //set the global author db entry
   db.set("globalAuthor:" + author, authorObj);

src/node/db/Pad.js

@@ -86,7 +86,7 @@ Pad.prototype.appendRevision = function appendRevision(aChangeset, author) {
   newRevData.changeset = aChangeset;
   newRevData.meta = {};
   newRevData.meta.author = author;
-  newRevData.meta.timestamp = new Date().getTime();
+  newRevData.meta.timestamp = Date.now();
 
   //ex. getNumForAuthor
   if(author != '')
@@ -739,7 +739,7 @@ Pad.prototype.addSavedRevision = function addSavedRevision(revNum, savedById, la
   savedRevision.revNum = revNum;
   savedRevision.savedById = savedById;
   savedRevision.label = label || "Revision " + revNum;
-  savedRevision.timestamp = new Date().getTime();
+  savedRevision.timestamp = Date.now();
   savedRevision.id = randomString(10);
 
   //save this new saved revision

src/node/db/SecurityManager.js

@@ -152,7 +152,7 @@ exports.checkAccess = function (padID, sessionCookie, token, password, callback)
               
               if(ERR(err, callback)) return;
               
-              var now = Math.floor(new Date().getTime()/1000);
+              var now = Math.floor(Date.now()/1000);
               
               //is it for this group?
               if(sessionInfo.groupID != groupID)

src/node/db/SessionManager.js

@@ -114,7 +114,7 @@ exports.createSession = function(groupID, authorID, validUntil, callback)
       }
     
       //check if validUntil is in the future
-      if(Math.floor(new Date().getTime()/1000) > validUntil)
+      if(Math.floor(Date.now()/1000) > validUntil)
       {
         callback(new customError("validUntil is in the past","apierror"));
         return;

src/node/handler/PadMessageHandler.js

@@ -355,7 +355,7 @@ exports.handleCustomObjectMessage = function (msg, sessionID, cb) {
  * @param msgString {String} the message we're sending
  */
 exports.handleCustomMessage = function (padID, msgString, cb) {
-  var time = new Date().getTime();
+  var time = Date.now();
   var msg = {
     type: 'COLLABROOM',
     data: {
@@ -375,7 +375,7 @@ exports.handleCustomMessage = function (padID, msgString, cb) {
  */
 function handleChatMessage(client, message)
 {
-  var time = new Date().getTime();
+  var time = Date.now();
   var userId = sessioninfos[client.id].author;
   var text = message.data.text;
   var padId = sessioninfos[client.id].padId;
@@ -1313,7 +1313,7 @@ function handleClientReady(client, message)
           "numConnectedUsers": roomClients.length,
           "readOnlyId": padIds.readOnlyPadId,
           "readonly": padIds.readonly,
-          "serverTimestamp": new Date().getTime(),
+          "serverTimestamp": Date.now(),
           "userId": author,
           "abiwordAvailable": settings.abiwordAvailable(),
           "sofficeAvailable": settings.sofficeAvailable(),

src/node/utils/Minify.js

@@ -204,7 +204,7 @@ function minify(req, res, next)
       res.setHeader('last-modified', date.toUTCString());
       res.setHeader('date', (new Date()).toUTCString());
       if (settings.maxAge !== undefined) {
-        var expiresDate = new Date((new Date()).getTime()+settings.maxAge*1000);
+        var expiresDate = new Date(Date.now()+settings.maxAge*1000);
         res.setHeader('expires', expiresDate.toUTCString());
         res.setHeader('cache-control', 'max-age=' + settings.maxAge);
       }