Add code style check error for using static_cast instead of toFoo function.

Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py

Index: Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py
diff --git a/Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py b/Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py
index ab53f175ab62f010f666f6647fd8fee0791511c1..61b6f7bb31133e259aaf7346eccc7ae3072372b6 100644
--- a/Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py
+++ b/Tools/Scripts/webkitpy/style/checkers/cpp_unittest.py
@@ -764,12 +764,17 @@ class CppStyleTest(CppStyleTestBase):
         self.assert_language_rules_check('foo.cpp', statement, error_message)
         self.assert_language_rules_check('foo.h', statement, error_message)
 
-    # Test for static_cast readability.
-    def test_static_cast_readability(self):
+    # Tests for static_cast readability.
+    def test_use_toFoo_readability(self):
         self.assert_lint(
             'Text* x = static_cast<Text*>(foo);',
-            'Consider using toText helper function in WebCore/dom/Text.h '
-            'instead of static_cast<Text*>'
+            'static_cast of class objects is not allowed. Use toText defined in Text.h.'
+            '  [readability/check] [4]')
+
+    def test_create_and_use_toFoo_readability(self):
+        self.assert_lint(
+            'HTMLButtonElement* x = static_cast<HTMLButtonElement*>(foo);',
+            'static_cast of class objects is not allowed. Add toHTMLButtonElement in HTMLButtonElement.h and use it instead.'
             '  [readability/check] [4]')
 
     # We cannot test this functionality because of difference of