Introduce visiblePositionOf() with PositionWithAffinity as replacement of VisiblePosition constructo

Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 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.
@@ skipping 2300 matching lines @@
 void Internals::setValueForUser(Element* element, const String& value)
 {
     toHTMLInputElement(element)->setValueForUser(value);
 }
 
 String Internals::textSurroundingNode(Node* node, int x, int y, unsigned long maxLength)
 {
     if (!node || !node->layoutObject())
         return String();
     blink::WebPoint point(x, y);
-    SurroundingText surroundingText(VisiblePosition(node->layoutObject()->positionForPoint(static_cast<IntPoint>(point))).deepEquivalent().parentAnchoredEquivalent(), maxLength);
+    SurroundingText surroundingText(visiblePositionOf(node->layoutObject()->positionForPoint(static_cast<IntPoint>(point))).deepEquivalent().parentAnchoredEquivalent(), maxLength);
     return surroundingText.content();
 }
 
 void Internals::setFocused(bool focused)
 {
     frame()->page()->focusController().setFocused(focused);
 }
 
 void Internals::setInitialFocus(bool reverse)
 {
@@ skipping 130 matching lines @@
 
     return animator->setScrollbarsVisibleForTesting(visible);
 }
 
 void Internals::forceRestrictIFramePermissions()
 {
     RuntimeEnabledFeatures::setRestrictIFramePermissionsEnabled(true);
 }
 
 } // namespace blink