Selection API: collapseToStart() and collapseToEnd() should recreate a Range.

third_party/WebKit/Source/core/editing/DOMSelection.cpp

Index: third_party/WebKit/Source/core/editing/DOMSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/DOMSelection.cpp b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
index 3ab419529702509df17ffbfecacbd19b315181d1..e38f0d7e42fdbde9b633cc4c0e733d008db35ad8 100644
--- a/third_party/WebKit/Source/core/editing/DOMSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
@@ -258,40 +258,54 @@ void DOMSelection::collapse(Node* node,
   cacheRangeIfSelectionOfDocument(newRange);
 }
 
+// https://www.w3.org/TR/selection-api/#dom-selection-collapsetoend
 void DOMSelection::collapseToEnd(ExceptionState& exceptionState) {
   if (!isAvailable())
     return;
 
-  const VisibleSelection& selection =
-      frame()->selection().computeVisibleSelectionInDOMTreeDeprecated();
-
-  if (selection.isNone()) {
+  // The method must throw InvalidStateError exception if the context object is
+  // empty.
+  if (rangeCount() == 0) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "there is no selection.");
     return;
   }
 
+  // Otherwise, it must create a new range, set both its start and end to the
+  // end of the context object's range,
+  Range* newRange = getRangeAt(0, ASSERT_NO_EXCEPTION)->cloneRange();
+  newRange->collapse(false);
+
+  // and then set the context object's range to the newly-created range.
   SelectionInDOMTree::Builder builder;
-  builder.collapse(selection.end());
+  builder.collapse(newRange->endPosition());
   frame()->selection().setSelection(builder.build());
+  cacheRangeIfSelectionOfDocument(newRange);
 }
 
+// https://www.w3.org/TR/selection-api/#dom-selection-collapsetostart
 void DOMSelection::collapseToStart(ExceptionState& exceptionState) {
   if (!isAvailable())
     return;
 
-  const VisibleSelection& selection =
-      frame()->selection().computeVisibleSelectionInDOMTreeDeprecated();
-
-  if (selection.isNone()) {
+  // The method must throw InvalidStateError ([DOM4]) exception if the context
+  // object is empty.
+  if (rangeCount() == 0) {
     exceptionState.throwDOMException(InvalidStateError,
                                      "there is no selection.");
     return;
   }
 
+  // Otherwise, it must create a new range, set both its start and end to the
+  // start of the context object's range,
+  Range* newRange = getRangeAt(0, ASSERT_NO_EXCEPTION)->cloneRange();
+  newRange->collapse(true);
+
+  // and then set the context object's range to the newly-created range.
   SelectionInDOMTree::Builder builder;
-  builder.collapse(selection.start());
+  builder.collapse(newRange->startPosition());
   frame()->selection().setSelection(builder.build());
+  cacheRangeIfSelectionOfDocument(newRange);
 }
 
 void DOMSelection::empty() {