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

tests/dom/utils.dart

-#library('TestUtils');
-
-/**
- * Verifies that [actual] has the same graph structure as [expected].
- * Detects cycles and DAG structure in Maps and Lists.
- */
-verifyGraph(expected, actual) {
-  var eItems = [];
-  var aItems = [];
-
-  message(path, reason) => path == ''
-      ? reason
-      : reason == null ? "path: $path" : "path: $path, $reason";
-
-  walk(path, expected, actual) {
-    if (expected is String || expected is num || expected == null) {
-      Expect.equals(expected, actual, message(path, 'not equal'));
-      return;
-    }
-
-    // Cycle or DAG?
-    for (int i = 0; i < eItems.length; i++) {
-      if (expected === eItems[i]) {
-        Expect.identical(aItems[i], actual, message(path, 'back or side edge'));
-        return;
-      }
-    }
-    eItems.add(expected);
-    aItems.add(actual);
-
-    if (expected is List) {
-      Expect.isTrue(actual is List, message(path, '$actual is List'));
-      Expect.equals(expected.length, actual.length,
-                    message(path, 'different list lengths'));
-      for (var i = 0; i < expected.length; i++) {
-        walk('$path[$i]', expected[i], actual[i]);
-      }
-      return;
-    }
-
-    if (expected is Map) {
-      Expect.isTrue(actual is Map, message(path, '$actual is Map'));
-      for (var key in expected.getKeys()) {
-        if (!actual.containsKey(key)) {
-          Expect.fail(message(path, 'missing key "$key"'));
-        }
-        walk('$path["$key"]',  expected[key], actual[key]);
-      }
-      for (var key in actual.getKeys()) {
-        if (!expected.containsKey(key)) {
-          Expect.fail(message(path, 'extra key "$key"'));
-        }
-      }
-      return;
-    }
-
-    Expect.fail('Unhandled type: $expected');
-  }
-
-  walk('', expected, actual);
-}