Make core/editing/ files to match Blink coding style

Source/core/editing/SmartReplaceICU.cpp

Index: Source/core/editing/SmartReplaceICU.cpp
diff --git a/Source/core/editing/SmartReplaceICU.cpp b/Source/core/editing/SmartReplaceICU.cpp
index efa779bdb7f262f737a111c1a808d3b551908ad9..5ce86c0fa6cea8a45ac33264822fff26c0fb7255 100644
--- a/Source/core/editing/SmartReplaceICU.cpp
+++ b/Source/core/editing/SmartReplaceICU.cpp
@@ -47,8 +47,8 @@ static void addAllCodePoints(USet* smartSet, const String& string)
 // except we use icu in place of CoreFoundations character classes.
 static USet* getSmartSet(bool isPreviousCharacter)
 {
-    static USet* preSmartSet = NULL;
-    static USet* postSmartSet = NULL;
+    static USet* preSmartSet = nullptr;
+    static USet* postSmartSet = nullptr;
     USet* smartSet = isPreviousCharacter ? preSmartSet : postSmartSet;
     if (!smartSet) {
         // Whitespace and newline (kCFCharacterSetWhitespaceAndNewline)