Copy lib/dom tests that use dart:html to lib/html.

tests/dom/native_gc_test.dart

-#library('NativeGCTest');
-#import('../../lib/unittest/unittest.dart');
-#import('../../lib/unittest/html_config.dart');
-#import('dart:html');
-
-main() {
-  useHtmlConfiguration();
-
-  test('EventListener', () {
-      final int N = 1000000;
-      final int M = 1000;
-
-      var div;
-      for (int i = 0; i < M; ++i) {
-        // This memory should be freed when the listener below is
-        // collected.
-        List l = new List(N);
-
-        // Record the iteration number.
-        l[N - 1] = i;
-
-        div = new Element.tag('div');
-        div.on['test'].add((_) {
-            // Only the final iteration's listener should be invoked.
-            // Note: the reference to l keeps the entire list alive.
-            Expect.equals(M - 1, l[N - 1]);
-          }, false);
-      }
-
-      final event = new Event('test');
-      div.on['test'].dispatch(event);
-  });
-}