avoid CPU-costly Date.toLocale(Date|Time)String() in logger page

source:
* gorhill/uBlock@02a79ea
* gorhill/uBlock@235d126
* gorhill/uBlock@3b41237

src/js/logger-ui.js

@@ -50,18 +50,6 @@ var prettyRequestTypes = {
     'xmlhttprequest': 'xhr'
 };
 
-var timeOptions = {
-    hour: '2-digit',
-    minute: '2-digit',
-    second: '2-digit',
-    hour12: false
-};
-
-var dateOptions = {
-    month: 'short',
-    day: '2-digit'
-};
-
 /******************************************************************************/
 
 // Adjust top padding of content table, to match that of toolbar height.
@@ -220,6 +208,12 @@ var createHiddenTextNode = function(text) {
 
 /******************************************************************************/
 
+var padTo2 = function(v) {
+    return v < 10 ? '0' + v : v;
+};
+
+/******************************************************************************/
+
 var createGap = function(tabId, url) {
     var tr = createRow('1');
     tr.classList.add('doc');
@@ -276,9 +270,11 @@ var renderLogEntry = function(entry) {
     }
 
     // Fields common to all rows.
-    var time = new Date(entry.tstamp);
-    tr.cells[0].textContent = time.toLocaleTimeString('fullwide', timeOptions);
-    tr.cells[0].title = time.toLocaleDateString('fullwide', dateOptions);
+    var time = logDate;
+    time.setTime(entry.tstamp - logDateTimezoneOffset);
+    tr.cells[0].textContent = padTo2(time.getUTCHours()) + ':' +
+                              padTo2(time.getUTCMinutes()) + ':' +
+                              padTo2(time.getSeconds());
 
     if ( entry.tab ) {
         tr.classList.add('tab');
@@ -296,6 +292,10 @@ var renderLogEntry = function(entry) {
     tbody.insertBefore(tr, tbody.firstChild);
 };
 
+// Reuse date objects.
+var logDate = new Date(),
+    logDateTimezoneOffset = logDate.getTimezoneOffset() * 60000;
+
 /******************************************************************************/
 
 var renderLogEntries = function(response) {