Fix textLength position adjustment for the "adjust spacing" case

third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp

 /*
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 190 matching lines @@
   bool is_vertical_text = !style.IsHorizontalWritingMode();
 
   // Calculate absolute length of whole text chunk (starting from text box
   // 'start', spanning 'length' text boxes).
   ChunkLengthAccumulator length_accumulator(is_vertical_text);
   length_accumulator.ProcessRange(box_start, box_end);
 
   if (process_text_length) {
     float chunk_length = length_accumulator.length();
     if (length_adjust == kSVGLengthAdjustSpacing) {
-      float text_length_shift = (desired_text_length - chunk_length) /
-                                length_accumulator.NumCharacters();

[fs, 2017/05/10 16:06:10]

When I had finished this I remembered/noticed that we have this calculation in
one more place =/ ('textLength' for <textPath>). Will fix that in a follow-up
CL.

+      float text_length_shift = 0;
+      if (length_accumulator.NumCharacters() > 1) {
+        text_length_shift = desired_text_length - chunk_length;
+        text_length_shift /= length_accumulator.NumCharacters() - 1;
+      }
       unsigned at_character = 0;
       for (auto box_iter = box_start; box_iter != box_end; ++box_iter) {
         Vector<SVGTextFragment>& fragments = (*box_iter)->TextFragments();
         if (fragments.IsEmpty())
           continue;
         ProcessTextLengthSpacingCorrection(is_vertical_text, text_length_shift,
                                            fragments, at_character);
       }
 
       // Fragments have been adjusted, we have to recalculate the chunk
@@ skipping 71 matching lines @@
     Vector<SVGTextFragment>& fragments) {
   for (SVGTextFragment& fragment : fragments) {
     if (is_vertical_text)
       fragment.y += text_anchor_shift;
     else
       fragment.x += text_anchor_shift;
   }
 }
 
 }  // namespace blink