Import dom/ from web-platform-tests

third_party/WebKit/LayoutTests/imported/web-platform-tests/dom/nodes/mutationobservers.js

+// Compares a mutation record to a predefined one
+// mutationToCheck is a mutation record from the user agent
+// expectedRecord is a mutation record minted by the test
+//    for expectedRecord, if properties are ommitted, they get default ones
+function checkRecords(target, mutationToCheck, expectedRecord) {
+  var mr1;
+  var mr2;
+
+
+  function checkField(property, isArray) {
+    var field = mr2[property];
+    if (isArray === undefined) {
+      isArray = false;
+    }
+    if (field instanceof Function) {
+      field = field();
+    } else if (field === undefined) {
+      if (isArray) {
+        field = new Array();
+      } else {
+        field = null;
+      }
+    }
+    if (isArray) {
+      assert_array_equals(mr1[property], field, property + " didn't match");
+    } else {
+      assert_equals(mr1[property], field, property + " didn't match");
+    }
+  }
+
+  assert_equals(mutationToCheck.length, expectedRecord.length, "mutation records must match");
+  for (var item = 0; item < mutationToCheck.length; item++) {
+    mr1 = mutationToCheck[item];
+    mr2 = expectedRecord[item];
+
+    if (mr2.target instanceof Function) {
+      assert_equals(mr1.target, mr2.target(), "target node must match");
+    } else if (mr2.target !== undefined) {
+      assert_equals(mr1.target, mr2.target, "target node must match");
+    } else {
+      assert_equals(mr1.target, target, "target node must match");
+    }
+
+    checkField("type");
+    checkField("addedNodes", true);
+    checkField("removedNodes", true);
+    checkField("previousSibling");
+    checkField("nextSibling");
+    checkField("attributeName");
+    checkField("attributeNamespace");
+    checkField("oldValue");
+  };
+}
+
+function runMutationTest(node, mutationObserverOptions, mutationRecordSequence, mutationFunction, description, target) {
+  var test = async_test(description);
+
+
+  function moc(mrl, obs) {
+    test.step(
+      function () {
+            if (target === undefined) target = node;
+            checkRecords(target, mrl, mutationRecordSequence);
+        test.done();
+      }
+     );
+  }
+
+  test.step(
+    function () {
+      (new MutationObserver(moc)).observe(node, mutationObserverOptions);
+      mutationFunction();
+    }
+  );
+  return mutationRecordSequence.length
+}