Fixes for re-enabling more MSVC level 4 warnings: Source/core/ edition

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 0898f2bae71f4423ccfdf505046a2429e77cd8fb..c888da23049d39d8c0009db256121216260de5fd 100644
--- a/Source/core/editing/TextIterator.cpp
+++ b/Source/core/editing/TextIterator.cpp
@@ -930,10 +930,11 @@ static bool shouldEmitNewlineAfterNode(Node& node)
     // Check if this is the very last renderer in the document.
     // If so, then we should not emit a newline.
     Node* next = &node;
-    while ((next = NodeTraversal::nextSkippingChildren(*next))) {
-        if (next->renderer())
+    do {
+        next = NodeTraversal::nextSkippingChildren(*next);
+        if (next && next->renderer())
             return true;
-    }
+    } while (next);
     return false;
 }