Copy and paste sometimes removes spaces between words.

Source/core/editing/TextIterator.cpp

Index: Source/core/editing/TextIterator.cpp
diff --git a/Source/core/editing/TextIterator.cpp b/Source/core/editing/TextIterator.cpp
index 7baf1c49df1e8a5c28764f5c2bc76f7cf5a144de..2d2dd979cc985ea40a61249737e1a13488499c89 100644
--- a/Source/core/editing/TextIterator.cpp
+++ b/Source/core/editing/TextIterator.cpp
@@ -268,6 +268,7 @@ TextIterator::TextIterator(const Range* range, TextIteratorBehaviorFlags behavio
     , 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());
@@ -744,6 +745,13 @@ void TextIterator::handleTextBox()
                 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;