Add support for Blob constructor in blobworkers test since BlobBuilder is deprecated and has been removed from firefox

whitespace change

fix cleanup for blobworker; ensure worker termination, ensure url revocation, and ensure addTest is only called once.

style fixes.

factor out cleanup & fail functions

feature-detects/workers/blobworkers.js

@@ -25,36 +25,57 @@ define(['Modernizr', 'addTest'], function( Modernizr, addTest ) {
       // these guys are notoriously peculiar.
       var BlobBuilder = window.MozBlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder || window.OBlobBuilder || window.BlobBuilder;
       var URL         = window.MozURL || window.webkitURL || window.MSURL || window.OURL || window.URL;
-      var data    = 'Modernizr';
-      var bb      = new BlobBuilder();
+      var data    = 'Modernizr',
+          blob,
+          bb,
+          worker,
+          url,
+          timeout,
+          scriptText = 'this.onmessage=function(e){postMessage(e.data)}';
 
-      bb.append('this.onmessage=function(e){postMessage(e.data)}');
+      try {
+        blob = new Blob([scriptText], {type:'text/javascript'});
+      } catch(e) {
+        // we'll fall back to the deprecated BlobBuilder
+      }
+      if (!blob) {
+        bb = new BlobBuilder();
+        bb.append(scriptText);
+        blob = bb.getBlob();
+      }
 
-      var url     = URL.createObjectURL(bb.getBlob());
-      var worker  = new Worker(url);
-
-      bb = null;
+      url = URL.createObjectURL(blob);
+      worker = new Worker(url);
 
       worker.onmessage = function(e) {
-        worker.terminate();
-        URL.revokeObjectURL(url);
         addTest('blobworkers', data === e.data);
-        worker = null;
+        cleanup();
       };
 
       // Just in case...
-      worker.onerror = function() {
-        addTest('blobworkers', false);
-        worker = null;
-      };
-
-      setTimeout(function() {
-        addTest('blobworkers', false);
-      }, 200);
+      worker.onerror = fail;
+      timeout = setTimeout(fail, 200);
 
       worker.postMessage(data);
     } catch (e) {
+      fail();
+    }
+
+    function fail() {
       addTest('blobworkers', false);
+      cleanup();
+    }
+
+    function cleanup() {
+      if (url) {
+        URL.revokeObjectURL(url);
+      }
+      if (worker) {
+        worker.terminate();
+      }
+      if (timeout) {
+        clearTimeout(timeout);
+      }
     }
   });
 });