lib: use Timer.now() in readline module

Using Date.now() introduces problems when operating under load or
otherwise with constrained resources. Use Timer.now() to mitigate.

The problem was identified in `test-readline-interface` where under
heavy load, `\r` and `\n` were received so far apart that they were
treated as separate line endings rather than a single line ending.
Switching to `Timer.now()` prevented this from happening.

PR-URL: #14681
Refs: #14674
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>

lib/readline.js

@@ -46,6 +46,8 @@ const {
   kClearScreenDown
 } = CSI;
 
+const now = process.binding('timer_wrap').Timer.now;
+
 const kHistorySize = 30;
 const kMincrlfDelay = 100;
 // \r\n, \n, or \r followed by something other than \n
@@ -395,7 +397,7 @@ Interface.prototype._normalWrite = function(b) {
   }
   var string = this._decoder.write(b);
   if (this._sawReturnAt &&
-      Date.now() - this._sawReturnAt <= this.crlfDelay) {
+      now() - this._sawReturnAt <= this.crlfDelay) {
     string = string.replace(/^\n/, '');
     this._sawReturnAt = 0;
   }
@@ -408,7 +410,7 @@ Interface.prototype._normalWrite = function(b) {
     this._line_buffer = null;
   }
   if (newPartContainsEnding) {
-    this._sawReturnAt = string.endsWith('\r') ? Date.now() : 0;
+    this._sawReturnAt = string.endsWith('\r') ? now() : 0;
 
     // got one or more newlines; process into "line" events
     var lines = string.split(lineEnding);
@@ -900,14 +902,14 @@ Interface.prototype._ttyWrite = function(s, key) {
 
     switch (key.name) {
       case 'return':  // carriage return, i.e. \r
-        this._sawReturnAt = Date.now();
+        this._sawReturnAt = now();
         this._line();
         break;
 
       case 'enter':
         // When key interval > crlfDelay
         if (this._sawReturnAt === 0 ||
-            Date.now() - this._sawReturnAt > this.crlfDelay) {
+            now() - this._sawReturnAt > this.crlfDelay) {
           this._line();
         }
         this._sawReturnAt = 0;