Cleanup: Start using toFoo methods as part of newly adopted coding guideline.

Source/core/css/StyleInvalidationAnalysis.cpp

Index: Source/core/css/StyleInvalidationAnalysis.cpp
diff --git a/Source/core/css/StyleInvalidationAnalysis.cpp b/Source/core/css/StyleInvalidationAnalysis.cpp
index ab0389da594581924da7a92769a2d28863f62b13..dbcd83f9b13e0f7a6cc2c62e3a4baa75d8218858 100644
--- a/Source/core/css/StyleInvalidationAnalysis.cpp
+++ b/Source/core/css/StyleInvalidationAnalysis.cpp
@@ -149,7 +149,7 @@ void StyleInvalidationAnalysis::analyzeStyleSheet(StyleSheetContents* styleSheet
             m_dirtiesAllStyle = true;
             return;
         }
-        StyleRule* styleRule = static_cast<StyleRule*>(rule);
+        StyleRule* styleRule = toStyleRule(rule);
         if (!determineSelectorScopes(styleRule->selectorList(), m_idScopes, m_classScopes)) {
             m_dirtiesAllStyle = true;
             return;