selection: Update addRange-nn.html for 20170227 draft.

third_party/WebKit/LayoutTests/external/wpt/selection/common.js

Index: third_party/WebKit/LayoutTests/external/wpt/selection/common.js
diff --git a/third_party/WebKit/LayoutTests/external/wpt/selection/common.js b/third_party/WebKit/LayoutTests/external/wpt/selection/common.js
index 51579e42444e3c723ed9c80283887d163bfd150d..3bdc509462bd3713fbdb5110c8739b911151f4e8 100644
--- a/third_party/WebKit/LayoutTests/external/wpt/selection/common.js
+++ b/third_party/WebKit/LayoutTests/external/wpt/selection/common.js
@@ -964,13 +964,25 @@ function setSelectionBackwards(endpoints) {
  * This function should be used in testharness tests.
  */
 function assertSelectionNoChange(func) {
-    var originalCount = getSelection().rangeCount;
+    var originalCount = selection.rangeCount;
     var originalRange = originalCount == 0 ? null : selection.getRangeAt(0);
+    var originalAnchorNode = selection.anchorNode;
+    var originalAnchorOffset = selection.anchorOffset;
+    var originalFocusNode = selection.focusNode;
+    var originalFocusOffset = selection.focusOffset;
 
     func();
 
     assert_equals(selection.rangeCount, originalCount,
         "The operation should not add Range");
+    assert_equals(selection.anchorNode, originalAnchorNode,
+        "The operation should not update anchorNode");
+    assert_equals(selection.anchorOffset, originalAnchorOffset,
+        "The operation should not update anchorOffset");
+    assert_equals(selection.focusNode, originalFocusNode,
+        "The operation should not update focusNode");
+    assert_equals(selection.focusOffset, originalFocusOffset,
+        "The operation should not update focusOffset");
     if (originalCount < 1)
         return;
     assert_equals(selection.getRangeAt(0), originalRange,