selection: Align collapse-NN.html and extend-NN.html to the latest draft.

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

 "use strict";
 
 // Also test a selection with no ranges
 testRanges.unshift("[]");
 
 // Run a subset of all of extend tests.
 // Huge number of tests in a single file causes problems. Each of
 // extend-NN.html runs a part of them.
 //
 // startIndex - Start index in testRanges array
@@ skipping 38 matching lines @@
     }
 }
 
 function testExtend(endpoints, target) {
     assert_equals(getSelection().rangeCount, endpoints.length/4,
         "Sanity check: rangeCount must be correct");
 
     var node = target[0];
     var offset = target[1];
 
+    // "If node's root is not the document associated with the context object,
+    // abort these steps."
+    if (!document.contains(node)) {
+        assertSelectionNoChange(function() {
+            selection.extend(node, offset);
+        });
+        return;
+    }
+
     // "If the context object's range is null, throw an InvalidStateError
     // exception and abort these steps."
     if (getSelection().rangeCount == 0) {
         assert_throws("INVALID_STATE_ERR", function() {
             selection.extend(node, offset);
         }, "extend() when rangeCount is 0 must throw InvalidStateError");
         return;
     }
 
     assert_equals(getSelection().getRangeAt(0).startContainer, endpoints[0],
@@ skipping 71 matching lines @@
         assert_equals(getSelection().anchorOffset, offset,
             "anchorOffset must be the offset passed to extend() if the node has a different root from the original range");
     }
     assert_equals(getSelection().focusNode, node,
         "focusNode must be the node passed to extend()");
     assert_equals(getSelection().focusOffset, offset,
         "focusOffset must be the offset passed to extend()");
     assert_not_equals(getSelection().getRangeAt(0), originalRange,
         "extend() must replace any existing range with a new one, not mutate the existing one");
 }