Get rid of clampScrollOffset and make maximumScrollPosition sane.

Source/core/layout/LayoutTextControlSingleLine.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 380 matching lines @@
 
     layoutObject->autoscroll(position);
 }
 
 LayoutUnit LayoutTextControlSingleLine::scrollWidth() const
 {
     if (LayoutBox* inner = innerEditorElement() ? innerEditorElement()->layoutBox() : 0) {
         // Adjust scrollWidth to inculde input element horizontal paddings and
         // decoration width
         LayoutUnit adjustment = clientWidth() - inner->clientWidth();
-        // TODO(leviw): We floor to avoid breaking JS that tries to scroll to
-        // scrollWidth - clientWidth.
-        // TODO(leviw): These values are broken when zooming. crbug.com/471412
-        return inner->scrollWidth().floor() + adjustment;
+        return inner->scrollWidth() + adjustment;
     }
     return LayoutBlockFlow::scrollWidth();
 }
 
 LayoutUnit LayoutTextControlSingleLine::scrollHeight() const
 {
     if (LayoutBox* inner = innerEditorElement() ? innerEditorElement()->layoutBox() : 0) {
         // Adjust scrollHeight to include input element vertical paddings and
         // decoration height
         LayoutUnit adjustment = clientHeight() - inner->clientHeight();
-        // TODO(leviw): We floor to avoid breaking JS that tries to scroll to
-        // scrollHeight - clientHeight.
-        // TODO(leviw): These values are broken when zooming. crbug.com/471412
-        return inner->scrollHeight().floor() + adjustment;
+        return inner->scrollHeight() + adjustment;
     }
     return LayoutBlockFlow::scrollHeight();
 }
 
 LayoutUnit LayoutTextControlSingleLine::scrollLeft() const
 {
     if (innerEditorElement())
         return innerEditorElement()->scrollLeft();
     return LayoutBlockFlow::scrollLeft();
 }
@@ skipping 16 matching lines @@
     if (innerEditorElement())
         innerEditorElement()->setScrollTop(newTop);
 }
 
 HTMLInputElement* LayoutTextControlSingleLine::inputElement() const
 {
     return toHTMLInputElement(node());
 }
 
 }