Adding tests for experimental Safe DOM creation technique.

tests/html/safe_dom_test.dart

+library safe_dom_test;
+
+import 'dart:async';
+import 'dart:html';
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+
+main() {
+  useHtmlConfiguration();
+
+  // Checks to see if any illegal properties were set via script.
+  var checkerScript = '''
+  window.addEventListener('message', function(e) {
+    if (e.data == 'check_unsafe') {
+      if (window.unsafe_value) {
+        window.postMessage('unsafe_check_failed', '*');
+      } else {
+        window.postMessage('unsafe_check_passed', '*');
+      }
+      //window.alert('checking!');
+    }
+  }, false);
+  ''';
+
+  var script = new ScriptElement();
+  script.text = checkerScript;
+  document.body.append(script);
+
+  var unsafeString =
+      '<img src="_.png" onerror="javascript:window.unsafe_value=1;" crap="1"/>';
+
+  test('Safe DOM', () {
+    var fragment = createContextualFragment(unsafeString);
+
+    expect(isSafe(), completion(true),
+        reason: 'Expected no unsafe code executed.');
+  });
+
+  // Make sure that scripts did get executed, so we know our detection works.
+  test('Unsafe Execution', () {
+    var div = new DivElement();
+    div.innerHtml = unsafeString;
+    // Crashing DRT ??
+    // var fragment = createContextualFragment(unsafeString);
+    // div.append(fragment);
+    // document.body.append(div)
+
+    expect(isSafe(), completion(false),
+        reason: 'Expected unsafe code was executed.');
+  });
+
+  test('Validity', () {
+    var fragment = createContextualFragment('<span>content</span>');
+    var div = new DivElement();
+    div.append(fragment);
+
+    expect(div.nodes.length, 1);
+    expect(div.nodes[0] is SpanElement, isTrue);
+  });
+}
+
+DocumentFragment createContextualFragment(String html, [String contextTag]) {
+  var doc = document.implementation.createHtmlDocument('');
+
+  var contextElement;
+  if (contextTag != null) {
+    contextElement = doc.$dom_createElement(contextTag);
+  } else {
+    contextElement = doc.body;
+  }
+
+  if (Range.supportsCreateContextualFragment) {
+    var range = doc.$dom_createRange();
+    range.selectNode(contextElement);
+    return range.createContextualFragment(html);
+  } else {
+    contextElement.innerHtml = html;
+    var fragment = new DocumentFragment();;
+    while (contextElement.$dom_firstChild != null) {
+      fragment.append(contextElement.$dom_firstChild);
+    }
+    return fragment;
+  }
+}
+
+// Delay to wait for the image load to fail.
+const Duration imageLoadDelay = const Duration(milliseconds: 500);
+
+Future<bool> isSafe() {
+  return new Future.delayed(imageLoadDelay).then((_) {
+    window.postMessage('check_unsafe', '*');
+  }).then((_) {
+    return window.onMessage.where(
+        (e) => e.data.startsWith('unsafe_check')).first;
+  }).then((e) {
+    return e.data == 'unsafe_check_passed';
+  });
+}