Avoid calling slower Node::firstChild() / Node::lastChild() when possible

Source/core/editing/CompositeEditCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2007, 2008 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 275 matching lines @@
 {
     applyCommandToComposite(InsertParagraphSeparatorCommand::create(document(), useDefaultParagraphElement, pasteBlockqutoeIntoUnquotedArea));
 }
 
 bool CompositeEditCommand::isRemovableBlock(const Node* node)
 {
     ASSERT(node);
     if (!isHTMLDivElement(*node))
         return false;
 
-    Node* parentNode = node->parentNode();
+    ContainerNode* parentNode = node->parentNode();
     if (parentNode && parentNode->firstChild() != parentNode->lastChild())
         return false;
 
     if (!toElement(node)->hasAttributes())
         return true;
 
     return false;
 }
 
 void CompositeEditCommand::insertNodeBefore(PassRefPtrWillBeRawPtr<Node> insertChild, PassRefPtrWillBeRawPtr<Node> refChild, ShouldAssumeContentIsAlwaysEditable shouldAssumeContentIsAlwaysEditable)
@@ skipping 571 matching lines @@
 
     // We are certain that the position is at a line break, but it may be a br or a preserved newline.
     if (isHTMLBRElement(*p.anchorNode())) {
         removeNode(p.anchorNode());
         return;
     }
 
     deleteTextFromNode(toText(p.anchorNode()), p.offsetInContainerNode(), 1);
 }
 
-PassRefPtrWillBeRawPtr<Node> CompositeEditCommand::insertNewDefaultParagraphElementAt(const Position& position)
+PassRefPtrWillBeRawPtr<Element> CompositeEditCommand::insertNewDefaultParagraphElementAt(const Position& position)
 {
     RefPtrWillBeRawPtr<Element> paragraphElement = createDefaultParagraphElement(document());
     paragraphElement->appendChild(createBreakElement(document()));
     insertNodeAt(paragraphElement, position);
     return paragraphElement.release();
 }
 
 // If the paragraph is not entirely within it's own block, create one and move the paragraph into
 // it, and return that block.  Otherwise return 0.
-PassRefPtrWillBeRawPtr<Node> CompositeEditCommand::moveParagraphContentsToNewBlockIfNecessary(const Position& pos)
+PassRefPtrWillBeRawPtr<Element> CompositeEditCommand::moveParagraphContentsToNewBlockIfNecessary(const Position& pos)
 {
     if (pos.isNull())
         return nullptr;
 
     document().updateLayoutIgnorePendingStylesheets();
 
     // It's strange that this function is responsible for verifying that pos has not been invalidated
     // by an earlier call to this function.  The caller, applyBlockStyle, should do this.
     VisiblePosition visiblePos(pos, VP_DEFAULT_AFFINITY);
     VisiblePosition visibleParagraphStart(startOfParagraph(visiblePos));
@@ skipping 30 matching lines @@
             return nullptr;
         } else if (isEndOfEditableOrNonEditableContent(visibleEnd)) {
             // At the end of the editable region. We can bail here as well.
             return nullptr;
         }
     }
 
     if (visibleParagraphEnd.isNull())
         return nullptr;
 
-    RefPtrWillBeRawPtr<Node> newBlock = insertNewDefaultParagraphElementAt(upstreamStart);
+    RefPtrWillBeRawPtr<Element> newBlock = insertNewDefaultParagraphElementAt(upstreamStart);
 
     bool endWasBr = isHTMLBRElement(*visibleParagraphEnd.deepEquivalent().deprecatedNode());
 
     moveParagraphs(visibleParagraphStart, visibleParagraphEnd, VisiblePosition(firstPositionInNode(newBlock.get())));
 
     if (newBlock->lastChild() && isHTMLBRElement(*newBlock->lastChild()) && !endWasBr)
         removeNode(newBlock->lastChild());
 
     return newBlock.release();
 }
@@ skipping 532 matching lines @@
 }
 
 void CompositeEditCommand::trace(Visitor* visitor)
 {
     visitor->trace(m_commands);
     visitor->trace(m_composition);
     EditCommand::trace(visitor);
 }
 
 } // namespace WebCore