Copy and paste sometimes removes spaces between words.

Source/core/editing/TextIterator.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov.
  *
  * 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 250 matching lines @@
     , m_entersTextControls(behavior & TextIteratorEntersTextControls)
     , m_emitsOriginalText(behavior & TextIteratorEmitsOriginalText)
     , m_handledFirstLetter(false)
     , m_ignoresStyleVisibility(behavior & TextIteratorIgnoresStyleVisibility)
     , m_stopsOnFormControls(behavior & TextIteratorStopsOnFormControls)
     , m_shouldStop(false)
     , m_emitsImageAltText(behavior & TextIteratorEmitsImageAltText)
     , m_entersAuthorShadowRoots(behavior & TextIteratorEntersAuthorShadowRoots)
     , m_emitsObjectReplacementCharacter(behavior & TextIteratorEmitsObjectReplacementCharacter)
     , m_breaksAtReplacedElement(!(behavior & TextIteratorDoesNotBreakAtReplacedElement))
+    , m_hasNodesFollowing(behavior & TextIteratorBehavesAsIfNodesFollowing)

[yosin_UTC9, 2015/01/14 01:46:20]

Do we need to have new behavior? It seems the issue is caused by word wrapping
and all call sites want to have a space at wrapped position.

[c.shu, 2015/01/14 21:13:41]

The bug is not a general issue. It only shows up when the text node is followed
by a non-text node. See function renderedText(...) in mark.cpp. The new behavior
is set when the textNode is not range->endContainer(). This info is lost when
constructing a new Range using textNode with startOffset and endOffset. So we
have to pass it through the constructor.

 {
     if (range)
         initialize(range->startPosition(), range->endPosition());
 }
 
 TextIterator::TextIterator(const Position& start, const Position& end, TextIteratorBehaviorFlags behavior)
     : m_startContainer(nullptr)
     , m_startOffset(0)
     , m_endContainer(nullptr)
     , m_endOffset(0)
@@ skipping 456 matching lines @@
                 // If we are doing a subrun that doesn't go to the end of the text box,
                 // come back again to finish handling this text box; don't advance to the next one.
                 if (static_cast<unsigned>(m_positionEndOffset) < textBoxEnd)
                     return;
 
                 // Advance and return
                 unsigned nextRunStart = nextTextBox ? nextTextBox->start() : str.length();
                 if (nextRunStart > runEnd)
                     m_lastTextNodeEndedWithCollapsedSpace = true; // collapsed space between runs or at the end
 
+                // Don't advance if last spaces, excluding '\n', are collapsed by next non-text box.
+                if (m_lastTextNodeEndedWithCollapsedSpace && !nextTextBox && m_hasNodesFollowing) {

[yosin_UTC9, 2015/01/14 01:46:20]

Sorry, I'm not sure why newline character is a special case.

[c.shu, 2015/01/14 21:13:41]

We don't want to restore the space for newline as it's taken care of already in
the exiting code. Otherwise, we see extra space in the paste.

+                    // None of the collapsed spaces should be '\n' but check the last one is enough.
+                    if (str[str.length() -1] != '\n')
+                        return;
+                }
+
                 m_textBox = nextTextBox;
                 if (renderer->containsReversedText())
                     ++m_sortedTextBoxesPosition;
                 return;
             }
             // Advance and continue
             m_textBox = nextTextBox;
             if (renderer->containsReversedText())
                 ++m_sortedTextBoxesPosition;
         }
@@ skipping 1673 matching lines @@
             resultEnd = collapseTo;
             return;
         }
     }
 
     CharacterIterator computeRangeIterator(inputStart, inputEnd, iteratorFlagsForFindPlainText);
     calculateCharacterSubrange(computeRangeIterator, matchStart, matchLength, resultStart, resultEnd);
 }
 
 }