Add test for DOM fileapi.

tests/html/fileapi_test.dart

+#library('fileapi');
+#import('../../lib/unittest/unittest.dart');
+#import('../../lib/unittest/html_config.dart');
+#import('dart:html');
+
+main() {
+  useHtmlConfiguration();
+  window.webkitRequestFileSystem(Window.TEMPORARY, 100, (fs) {
+    // FIXME: add types to callback arguments after migration to wrapperless dart:html.
+    asyncTest('getDirectory', 2, () {
+      Expect.throws(() => fs.root.getDirectory('directory1', {'x': true}, (e) {}));
+
+      fs.root.getDirectory('directory2', {}, (e) {

[Anton Muhin, 2012/05/15 18:32:23]

this is very hard to read, but luckily starting from 2nd, arguments are named,
may you use those names?

fs.root.getDirectory('directory2',
  flags: {},
  successCallback: (e) { ... }

???

[podivilov, 2012/05/16 13:49:25]

Done.

+        Expect.fail('Should not be reached');
+        callbackDone();
+      }, (e) {
+        Expect.equals(FileError.NOT_FOUND_ERR, e.code);
+        callbackDone();
+      });
+
+      fs.root.getDirectory('directory3', {'create': true}, (e) {
+        Expect.equals('directory3', e.name);
+        callbackDone();
+      }, (e) {
+        Expect.fail('Got file error: ${e.code}');
+        callbackDone();
+      });
+    });
+
+    asyncTest('getFile', 2, () {
+      Expect.throws(() => fs.root.getFile('file1', {'x': true}, (e) {}));
+
+      fs.root.getDirectory('file2', {}, (e) {
+        Expect.fail('Should not be reached');
+        callbackDone();
+      }, (e) {
+        Expect.equals(FileError.NOT_FOUND_ERR, e.code);
+        callbackDone();
+      });
+
+      fs.root.getDirectory('file3', {'create': true}, (e) {
+        Expect.equals('file3', e.name);
+        callbackDone();
+      }, (e) {
+        Expect.fail('Got file error: ${e.code}');
+        callbackDone();
+      });
+    });
+  });
+}