boundaryTextInserted/Removed() should not call markValid() for irrelavent changes

third_party/WebKit/Source/core/dom/Range.cpp

Index: third_party/WebKit/Source/core/dom/Range.cpp
diff --git a/third_party/WebKit/Source/core/dom/Range.cpp b/third_party/WebKit/Source/core/dom/Range.cpp
index c2b287b8330d9d4973587d90574795a344301f98..7f1ff8dfd65e10d0ac5e7278a20194cfd156df7f 100644
--- a/third_party/WebKit/Source/core/dom/Range.cpp
+++ b/third_party/WebKit/Source/core/dom/Range.cpp
@@ -1386,9 +1386,9 @@ void Range::nodeWillBeRemoved(Node& node)
 
 static inline void boundaryTextInserted(RangeBoundaryPoint& boundary, Node* text, unsigned offset, unsigned length)
 {
-    boundary.markValid();
     if (boundary.container() != text)
         return;
+    boundary.markValid();
     unsigned boundaryOffset = boundary.offset();
     if (offset >= boundaryOffset)
         return;
@@ -1405,9 +1405,9 @@ void Range::didInsertText(Node* text, unsigned offset, unsigned length)
 
 static inline void boundaryTextRemoved(RangeBoundaryPoint& boundary, Node* text, unsigned offset, unsigned length)
 {
-    boundary.markValid();
     if (boundary.container() != text)
         return;
+    boundary.markValid();

[yosin_UTC9, 2016/08/19 06:02:43]

Sorry, I don't understand this change.

Changing data in CharacterData node doesn't affect offset in child node of
container node.
When we move |markValid()| here and |boundaryTextInserted()|, each text data
change invalidate valid offset in container of |RangeBoundaryPoint|.

[yosin_UTC9, 2016/08/19 06:25:48]

Discussed offline. I understand this patch is correct.
Note: when container node is CharacterData, offset in RangeBoundaryPoint is
always valid. So, we don't need to update dom tree version in RBP.

     unsigned boundaryOffset = boundary.offset();
     if (offset >= boundaryOffset)
         return;