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

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 410 matching lines @@
   else
     return;
 
   // TODO(editing-dev): The use of updateStyleAndLayoutIgnorePendingStylesheets
   // needs to be audited.  See http://crbug.com/590369 for more details.
   frame()->document()->updateStyleAndLayoutIgnorePendingStylesheets();
 
   frame()->selection().modify(alter, direction, granularity);
 }
 
+// https://www.w3.org/TR/selection-api/#dom-selection-extend
 void DOMSelection::extend(Node* node,
                           int offset,
                           ExceptionState& exceptionState) {
   DCHECK(node);
-  // https://www.w3.org/TR/selection-api/#dom-selection-extend
+  // 1. If node's root is not the document associated with the context object,
+  // abort these steps.
+  if (!isValidForPosition(node))
+    return;
 
   // 2. If the context object is empty, throw an InvalidStateError exception and
   // abort these steps.
   if (rangeCount() == 0) {
     exceptionState.throwDOMException(
         InvalidStateError, "This Selection object doesn't have any Ranges.");
     return;
   }
 
   if (offset < 0) {
     exceptionState.throwDOMException(
         IndexSizeError, String::number(offset) + " is not a valid offset.");
     return;
   }
   Range::checkNodeWOffset(node, offset, exceptionState);
   if (exceptionState.hadException())
     return;
 
-  // 1. If node's root is not the document associated with the context object,
-  // abort these steps.
-  if (!isValidForPosition(node))
-    return;
-
   // 3. Let oldAnchor and oldFocus be the context object's anchor and focus, and
   // let newFocus be the boundary point (node, offset).
   const Position& oldAnchor = anchorPosition();
   DCHECK(!oldAnchor.isNull());
   const Position newFocus(node, offset);
 
   clearCachedRangeIfSelectionOfDocument();
 
   // 4. Let newRange be a new range.
   Range* newRange = Range::create(*frame()->document());
@@ skipping 340 matching lines @@
     m_treeScope->document().addConsoleMessage(
         ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
 }
 
 DEFINE_TRACE(DOMSelection) {
   visitor->trace(m_treeScope);
   ContextClient::trace(visitor);
 }
 
 }  // namespace blink