Make Range::createAdjustedToTreeScope() to handle the shadow root at end of document tree correctly

third_party/WebKit/Source/core/dom/RangeTest.cpp

Index: third_party/WebKit/Source/core/dom/RangeTest.cpp
diff --git a/third_party/WebKit/Source/core/dom/RangeTest.cpp b/third_party/WebKit/Source/core/dom/RangeTest.cpp
index 098dd81ef8c0e1c357fb3724e918833e7fa5a659..6c5f21324d4554dfe36c425de7ce5222f5917162 100644
--- a/third_party/WebKit/Source/core/dom/RangeTest.cpp
+++ b/third_party/WebKit/Source/core/dom/RangeTest.cpp
@@ -41,6 +41,18 @@ HTMLDocument& RangeTest::document() const {
   return *m_document;
 }
 
+TEST_F(RangeTest, createAdjustedToTreeScopeWithPositionInShadowTree) {
+  document().body()->setInnerHTML("<div><select><option>012</option></div>");
+  Element* const selectElement = document().querySelector("select");
+  const Position& position =
+      Position::afterNode(selectElement->userAgentShadowRoot());
+  Range* const range = Range::createAdjustedToTreeScope(document(), position);
+  EXPECT_EQ(range->startContainer(), selectElement->parentNode());
+  EXPECT_EQ(static_cast<unsigned>(range->startOffset()),
+            selectElement->nodeIndex());
+  EXPECT_TRUE(range->collapsed());
+}
+
 TEST_F(RangeTest, SplitTextNodeRangeWithinText) {
   document().body()->setInnerHTML("1234");
   Text* oldText = toText(document().body()->firstChild());