Introduce use counters for shadow DOM handling in plainText()

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index f55ea51759ea5c6abe84509bb8d47b5478aaf987..f1e159b23ffbf7324226f8b2a6a64ced6eb9962d 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -2497,7 +2497,7 @@ String Element::innerText()
     if (!layoutObject())
         return textContent(true);
 
-    return plainText(Position(this, Position::PositionIsBeforeChildren), Position(this, Position::PositionIsAfterChildren));
+    return plainText(Position(this, Position::PositionIsBeforeChildren), Position(this, Position::PositionIsAfterChildren), TextIteratorForInnerText);

[yoichio, 2015/07/02 06:28:39]

Why do't you call UseCounter::count here directly?

[yosin_UTC9, 2015/07/02 06:40:29]

I would like to count only if |plainText()| handles shadow DOM tree.

[yoichio, 2015/07/02 07:10:32]

Can't we check that here?

[yosin_UTC9, 2015/07/02 08:08:31]

Yes, we can. But, we need to traverse tree here. We don't want to traverse
twice, once for here and another is |plaintText()|.

 }
 
 String Element::outerText()