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

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

 /*
  * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 240 matching lines @@
 
   // 6. Set the context object's range to newRange.
   frame()->selection().setSelection(
       SelectionInDOMTree::Builder()
           .collapse(Position(node, offset))
           .setIsDirectional(frame()->selection().isDirectional())
           .build());
   cacheRangeIfSelectionOfDocument(newRange);
 }
 
-// https://www.w3.org/TR/selection-api/#dom-selection-collapsetoend
 void DOMSelection::collapseToEnd(ExceptionState& exceptionState) {
   if (!isAvailable())
     return;
 
-  // The method must throw InvalidStateError exception if the context object is
-  // empty.
-  if (rangeCount() == 0) {
+  const VisibleSelection& selection =
+      frame()->selection().computeVisibleSelectionInDOMTreeDeprecated();
+
+  if (selection.isNone()) {
     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(newRange->endPosition());
+  builder.collapse(selection.end());
   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;
 
-  // The method must throw InvalidStateError ([DOM4]) exception if the context
-  // object is empty.
-  if (rangeCount() == 0) {
+  const VisibleSelection& selection =
+      frame()->selection().computeVisibleSelectionInDOMTreeDeprecated();
+
+  if (selection.isNone()) {
     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(newRange->startPosition());
+  builder.collapse(selection.start());
   frame()->selection().setSelection(builder.build());
-  cacheRangeIfSelectionOfDocument(newRange);
 }
 
 void DOMSelection::empty() {
   if (!isAvailable())
     return;
   frame()->selection().clear();
 }
 
 void DOMSelection::setBaseAndExtent(Node* baseNode,
                                     int baseOffset,
@@ skipping 504 matching lines @@
     m_treeScope->document().addConsoleMessage(
         ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
 }
 
 DEFINE_TRACE(DOMSelection) {
   visitor->trace(m_treeScope);
   ContextClient::trace(visitor);
 }
 
 }  // namespace blink