fix benchmark.

lib/term.js

@@ -525,7 +525,7 @@ Terminal.prototype.open = function(parent) {
         : null;
 
     // Does IE9 do this?
-    if (~navigator.userAgent.indexOf('MSIE')) {
+    if (self.isMSIE) {
       button = button === 1 ? 0 : button === 4 ? 1 : button;
     }
 
@@ -559,6 +559,11 @@ Terminal.prototype.open = function(parent) {
   this.element.style.backgroundColor = Terminal.defaultColors.bg;
   this.element.style.color = Terminal.defaultColors.fg;
 
+  if (this.context.navigator && this.context.navigator.userAgent) {
+    this.isMac = !!~this.context.navigator.userAgent.indexOf('Mac');
+    this.isMSIE = !!~this.context.navigator.userAgent.indexOf('MSIE');
+  }
+
   // this.emit('open');
 };
 
@@ -753,7 +758,7 @@ Terminal.prototype.bindMouse = function() {
             ? ev.which - 1
             : null;
 
-        if (~navigator.userAgent.indexOf('MSIE')) {
+        if (self.isMSIE) {
           button = button === 1 ? 0 : button === 4 ? 1 : button;
         }
         break;
@@ -2343,7 +2348,7 @@ Terminal.prototype.keyDown = function(ev) {
           // ^] - group sep
           key = String.fromCharCode(29);
         }
-      } else if ((!isMac && ev.altKey) || (isMac && ev.metaKey)) {
+      } else if ((!this.isMac && ev.altKey) || (this.isMac && ev.metaKey)) {
         if (ev.keyCode >= 65 && ev.keyCode <= 90) {
           key = '\x1b' + String.fromCharCode(ev.keyCode + 32);
         } else if (ev.keyCode === 192) {
@@ -4417,8 +4422,6 @@ function inherits(child, parent) {
   child.prototype = new f;
 }
 
-var isMac = ~navigator.userAgent.indexOf('Mac');
-
 // if bold is broken, we can't
 // use it in the terminal.
 function isBoldBroken(document) {
@@ -4506,7 +4509,6 @@ matchColor.distance = function(r1, g1, b1, r2, g2, b2) {
  */
 
 Terminal.EventEmitter = EventEmitter;
-Terminal.isMac = isMac;
 Terminal.inherits = inherits;
 Terminal.on = on;
 Terminal.off = off;