Have Node::document() return a reference instead of a pointer

Source/core/rendering/RenderTextControlSingleLine.cpp

 /**
  * Copyright (C) 2006, 2007, 2010 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 235 matching lines @@
     RenderObject* innerTextRenderer = innerTextElement()->renderer();
     if (innerTextRenderer && diff == StyleDifferenceLayout)
         innerTextRenderer->setNeedsLayout();
     if (HTMLElement* placeholder = inputElement()->placeholderElement())
         placeholder->setInlineStyleProperty(CSSPropertyTextOverflow, textShouldBeTruncated() ? CSSValueEllipsis : CSSValueClip);
     setHasOverflowClip(false);
 }
 
 void RenderTextControlSingleLine::capsLockStateMayHaveChanged()
 {
-    if (!node() || !document())
+    if (!node())
         return;
 
     // Only draw the caps lock indicator if these things are true:
     // 1) The field is a password field
     // 2) The frame is active
     // 3) The element is focused
     // 4) The caps lock is on
     bool shouldDrawCapsLockIndicator = false;
 
-    if (Frame* frame = document()->frame())
-        shouldDrawCapsLockIndicator = inputElement()->isPasswordField() && frame->selection()->isFocusedAndActive() && document()->focusedElement() == node() && PlatformKeyboardEvent::currentCapsLockState();
+    if (Frame* frame = document().frame())
+        shouldDrawCapsLockIndicator = inputElement()->isPasswordField() && frame->selection()->isFocusedAndActive() && document().focusedElement() == node() && PlatformKeyboardEvent::currentCapsLockState();
 
     if (shouldDrawCapsLockIndicator != m_shouldDrawCapsLockIndicator) {
         m_shouldDrawCapsLockIndicator = shouldDrawCapsLockIndicator;
         repaint();
     }
 }
 
 bool RenderTextControlSingleLine::hasControlClip() const
 {
     // Apply control clip for text fields with decorations.
@@ skipping 87 matching lines @@
     if (textBlockStyle->fontMetrics().lineSpacing() > lineHeight(true, HorizontalLine, PositionOfInteriorLineBoxes))
         textBlockStyle->setLineHeight(RenderStyle::initialLineHeight());
 
     textBlockStyle->setDisplay(BLOCK);
 
     return textBlockStyle.release();
 }
 
 bool RenderTextControlSingleLine::textShouldBeTruncated() const
 {
-    return document()->focusedElement() != node() && style()->textOverflow() == TextOverflowEllipsis;
+    return document().focusedElement() != node() && style()->textOverflow() == TextOverflowEllipsis;
 }
 
 void RenderTextControlSingleLine::autoscroll(const IntPoint& position)
 {
     RenderBox* renderer = innerTextElement()->renderBox();
     if (!renderer)
         return;
     RenderLayer* layer = renderer->layer();
     if (layer)
         layer->autoscroll(position);
@@ skipping 38 matching lines @@
     if (innerTextElement())
         innerTextElement()->setScrollTop(newTop);
 }
 
 HTMLInputElement* RenderTextControlSingleLine::inputElement() const
 {
     return toHTMLInputElement(node());
 }
 
 }