Fixup a bug about SVG text selection.

Source/core/layout/svg/LayoutSVGInlineText.cpp

 /*
  * Copyright (C) 2006 Oliver Hunt <ojh16@student.canterbury.ac.nz>
  * Copyright (C) 2006 Apple Computer Inc.
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2008 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * 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
@@ skipping 159 matching lines @@
     SVGInlineTextBox* closestDistanceBox = 0;
 
     AffineTransform fragmentTransform;
     for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
         if (!box->isSVGInlineTextBox())
             continue;
 
         SVGInlineTextBox* textBox = toSVGInlineTextBox(box);
         Vector<SVGTextFragment>& fragments = textBox->textFragments();
 
-        unsigned textFragmentsSize = fragments.size();
+        unsigned textFragmentsSize = fragments.size(); 
         for (unsigned i = 0; i < textFragmentsSize; ++i) {
             const SVGTextFragment& fragment = fragments.at(i);
             FloatRect fragmentRect(fragment.x, fragment.y - baseline, fragment.width, fragment.height);
             fragment.buildFragmentTransform(fragmentTransform);
             fragmentRect = fragmentTransform.mapRect(fragmentRect);
+            // This is edge selection. If there is absolute-point between center and right edge of fragmentRect,
+            // selects rightEndge. In other cases selects left edge. 
+            FloatPoint selectedEdge;
+            if (absolutePoint.x() > fragmentRect.center().x() && absolutePoint.x() < fragmentRect.maxX()) {

[fs, 2015/04/23 16:29:51]

Why not just pick the closest edge? Using the left edge when the point is
outside to the right doesn't seem very good.

+                selectedEdge = fragmentRect.rightEdgeMidPoint();

[fs, 2015/04/23 16:29:51]

Rather than adding these new methods, you could do:

FloatPoint selectedEdge = fragmentRect.center();
...
selectedEdge.move(-fragmentRect.width() / 2, 0); // left edge
...
selectedEdge.move(fragmentRect.width() / 2, 0); // right edge

+            } else {
+                selectedEdge = fragmentRect.leftEdgeMidPoint();
+            }
 
-            float distance = powf(fragmentRect.x() - absolutePoint.x(), 2) +
-                powf(fragmentRect.y() + fragmentRect.height() / 2 - absolutePoint.y(), 2);
+            float distance = (selectedEdge - absolutePoint).diagonalLengthSquared();
 
             if (distance < closestDistance) {
                 closestDistance = distance;
                 closestDistanceBox = textBox;
                 closestDistanceFragment = &fragment;
                 closestDistancePosition = fragmentRect.x();
             }
         }
     }
 
@@ skipping 45 matching lines @@
 
 PassRefPtr<StringImpl> LayoutSVGInlineText::originalText() const
 {
     RefPtr<StringImpl> result = LayoutText::originalText();
     if (!result)
         return nullptr;
     return applySVGWhitespaceRules(result, style() && style()->whiteSpace() == PRE);
 }
 
 }