Implement File constructor.

LayoutTests/resources/js-test.js

 // svg/dynamic-updates tests set enablePixelTesting=true, as we want to dump text + pixel results
 if (self.testRunner) {
     if (self.enablePixelTesting)
         testRunner.dumpAsTextWithPixelResults();
     else
         testRunner.dumpAsText();
 }
 
 var description, debug, successfullyParsed, errorMessage;
 
@@ skipping 77 matching lines @@
 
     if (!isWorker()) {
         window.addEventListener('DOMContentLoaded', handleTestFinished, false);
         insertStyleSheet();
     }
 
     if (!self.isOnErrorTest) {
         self.onerror = function(message)
         {
             errorMessage = message;
+            finishJSTest();
         };
     }
 })();
 
 function isWorker()
 {
     // It's conceivable that someone would stub out 'document' in a worker so
     // also check for childNodes, an arbitrary DOM-related object that is
     // meaningless in a WorkerContext.
     return (typeof document === 'undefined' || typeof document.childNodes === 'undefined') && !!self.importScripts;
@@ skipping 577 matching lines @@
     testPassed = function(msg) {
         workerPort.postMessage('PASS:' + msg);
     }
     finishJSTest = function() {
         workerPort.postMessage('DONE:');
     }
     debug = function(msg) {
         workerPort.postMessage(msg);
     }
 }