Update editing classes to use OVERRIDE / FINAL when needed

Source/core/editing/InsertTextCommand.h

Index: Source/core/editing/InsertTextCommand.h
diff --git a/Source/core/editing/InsertTextCommand.h b/Source/core/editing/InsertTextCommand.h
index 10c8d80ea49d290e314ac52e928361afa59edba2..d8636503e162f3d3282b7c0e72897260d079d512 100644
--- a/Source/core/editing/InsertTextCommand.h
+++ b/Source/core/editing/InsertTextCommand.h
@@ -41,7 +41,7 @@ protected:
     TextInsertionMarkerSupplier() { }
 };
 
-class InsertTextCommand : public CompositeEditCommand {
+class InsertTextCommand FINAL : public CompositeEditCommand {
 public:
     enum RebalanceType {
         RebalanceLeadingAndTrailingWhitespaces,
@@ -66,7 +66,7 @@ private:
 
     void deleteCharacter();
 
-    virtual void doApply();
+    virtual void doApply() OVERRIDE;
 
     Position positionInsideTextNode(const Position&);
     Position insertTab(const Position&);