Get rid of inefficient uses of childNodeCount()

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 b85b148eaf9608052ac88662b451df18dd732357..ca94a641bb2847e5baefe03230aa92da7ef916c5 100644
--- a/Source/core/editing/TextIterator.cpp
+++ b/Source/core/editing/TextIterator.cpp
@@ -1183,15 +1183,15 @@ SimplifiedBackwardsTextIterator::SimplifiedBackwardsTextIterator(const Range* r,
     int startOffset = r->startOffset();
     int endOffset = r->endOffset();
 
-    if (!startNode->offsetInCharacters()) {
-        if (startOffset >= 0 && startOffset < static_cast<int>(startNode->childNodeCount())) {
-            startNode = startNode->childNode(startOffset);
+    if (!startNode->offsetInCharacters() && startOffset >= 0) {
+        if (Node* childAtOffset = startNode->childNode(startOffset)) {

[Inactive, 2014/02/19 04:13:33]

ContainerNode::childNode(index) will return 0 if the offset is greater than the
number of children anyway.

[eseidel, 2014/02/19 05:39:54]

This seems like rather odd behavior to depend on.  I'm a bit surprised it
doesn't ASSERT.

If you're going to depend on this behavior I would leave a comment to explain
that.

[Inactive, 2014/02/19 14:28:15]

Yes, I don't have a better proposal than this at the moment. I will add a
comment to explain.

+            startNode = childAtOffset;
             startOffset = 0;
         }
     }
-    if (!endNode->offsetInCharacters()) {
-        if (endOffset > 0 && endOffset <= static_cast<int>(endNode->childNodeCount())) {
-            endNode = endNode->childNode(endOffset - 1);
+    if (!endNode->offsetInCharacters() && endOffset > 0) {
+        if (Node* childAtOffset = endNode->childNode(endOffset - 1)) {
+            endNode = childAtOffset;
             endOffset = lastOffsetInNode(endNode);
         }
     }