Pasting \n into an empty TEXTAREA should set the caret after the \n.

third_party/WebKit/Source/core/editing/commands/ReplaceSelectionCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010, 2011 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1311 matching lines @@
         if (m_endOfInsertedContent.isOrphan())
             m_endOfInsertedContent = mostBackwardCaretPosition(endingSelection().visibleEnd().deepEquivalent());
     }
 
     Position lastPositionToSelect;
     if (fragment.hasInterchangeNewlineAtEnd()) {
         VisiblePosition endOfInsertedContent = positionAtEndOfInsertedContent();
         VisiblePosition next = nextPositionOf(endOfInsertedContent, CannotCrossEditingBoundary);
 
         if (selectionEndWasEndOfParagraph || !isEndOfParagraph(endOfInsertedContent) || next.isNull()) {
-            if (!isStartOfParagraph(endOfInsertedContent)) {
+            if (HTMLTextFormControlElement* textControl = enclosingTextFormControl(currentRoot)) {
+                if (!insertedNodes.lastLeafInserted()->nextSibling()) {
+                    insertNodeAfter(textControl->createPlaceholderBreakElement(), insertedNodes.lastLeafInserted(), editingState);
+                    if (editingState->isAborted())
+                        return;
+                }
+                setEndingSelection(createVisiblePosition(positionAfterNode(insertedNodes.lastLeafInserted())));
+                // Select up to the paragraph separator that was added.
+                lastPositionToSelect = endingSelection().visibleStart().deepEquivalent();
+            } else if (!isStartOfParagraph(endOfInsertedContent)) {
                 setEndingSelection(endOfInsertedContent);
                 Element* enclosingBlockElement = enclosingBlock(endOfInsertedContent.deepEquivalent().anchorNode());
                 if (isListItem(enclosingBlockElement)) {
                     RefPtrWillBeRawPtr<HTMLLIElement> newListItem = HTMLLIElement::create(document());
                     insertNodeAfter(newListItem, enclosingBlockElement, editingState);
                     if (editingState->isAborted())
                         return;
                     setEndingSelection(createVisiblePosition(firstPositionInNode(newListItem.get())));
-                } else if (HTMLTextFormControlElement* textControl = enclosingTextFormControl(enclosingBlockElement)) {
-                    insertNodeAfter(textControl->createPlaceholderBreakElement(), insertedNodes.lastLeafInserted(), editingState);
-                    if (editingState->isAborted())
-                        return;
-                    setEndingSelection(createVisiblePosition(positionAfterNode(insertedNodes.lastLeafInserted())));
                 } else {
                     // Use a default paragraph element (a plain div) for the empty paragraph, using the last paragraph
                     // block's style seems to annoy users.
                     insertParagraphSeparator(editingState, true, !startIsInsideMailBlockquote && highestEnclosingNodeOfType(endOfInsertedContent.deepEquivalent(),
                         isMailHTMLBlockquoteElement, CannotCrossEditingBoundary, insertedNodes.firstNodeInserted()->parentNode()));
                     if (editingState->isAborted())
                         return;
                 }
 
                 // Select up to the paragraph separator that was added.
@@ skipping 343 matching lines @@
     visitor->trace(m_startOfInsertedContent);
     visitor->trace(m_endOfInsertedContent);
     visitor->trace(m_insertionStyle);
     visitor->trace(m_documentFragment);
     visitor->trace(m_startOfInsertedRange);
     visitor->trace(m_endOfInsertedRange);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink