Don't fail tests if progress can't be rendered

This allows mocha to be used on Firefox < 3.5

lib/browser/progress.js

@@ -1,4 +1,3 @@
-
 /**
  * Expose `Progress`.
  */
@@ -87,39 +86,40 @@ Progress.prototype.update = function(n){
  */
 
 Progress.prototype.draw = function(ctx){
-  var percent = Math.min(this.percent, 100)
-    , size = this._size
-    , half = size / 2
-    , x = half
-    , y = half
-    , rad = half - 1
-    , fontSize = this._fontSize;
-
-  ctx.font = fontSize + 'px ' + this._font;
-
-  var angle = Math.PI * 2 * (percent / 100);
-  ctx.clearRect(0, 0, size, size);
-
-  // outer circle
-  ctx.strokeStyle = '#9f9f9f';
-  ctx.beginPath();
-  ctx.arc(x, y, rad, 0, angle, false);
-  ctx.stroke();
-
-  // inner circle
-  ctx.strokeStyle = '#eee';
-  ctx.beginPath();
-  ctx.arc(x, y, rad - 1, 0, angle, true);
-  ctx.stroke();
-
-  // text
-  var text = this._text || (percent | 0) + '%'
-    , w = ctx.measureText(text).width;
-
-  ctx.fillText(
-      text
-    , x - w / 2 + 1
-    , y + fontSize / 2 - 1);
-
+  try {
+    var percent = Math.min(this.percent, 100)
+      , size = this._size
+      , half = size / 2
+      , x = half
+      , y = half
+      , rad = half - 1
+      , fontSize = this._fontSize;
+
+    ctx.font = fontSize + 'px ' + this._font;
+
+    var angle = Math.PI * 2 * (percent / 100);
+    ctx.clearRect(0, 0, size, size);
+
+    // outer circle
+    ctx.strokeStyle = '#9f9f9f';
+    ctx.beginPath();
+    ctx.arc(x, y, rad, 0, angle, false);
+    ctx.stroke();
+
+    // inner circle
+    ctx.strokeStyle = '#eee';
+    ctx.beginPath();
+    ctx.arc(x, y, rad - 1, 0, angle, true);
+    ctx.stroke();
+
+    // text
+    var text = this._text || (percent | 0) + '%'
+      , w = ctx.measureText(text).width;
+
+    ctx.fillText(
+        text
+      , x - w / 2 + 1
+      , y + fontSize / 2 - 1);
+  } catch (ex) {} //don't fail if we can't render progress
   return this;
 };