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

Source/core/css/StyleRule.cpp

Index: Source/core/css/StyleRule.cpp
diff --git a/Source/core/css/StyleRule.cpp b/Source/core/css/StyleRule.cpp
index 2fc1fdafbc3d982b658b041cee8d11864391cad8..3008e849c37afa293d2ff8bba77ee4635d1489cd 100644
--- a/Source/core/css/StyleRule.cpp
+++ b/Source/core/css/StyleRule.cpp
@@ -59,7 +59,7 @@ void StyleRuleBase::destroy()
 {
     switch (type()) {
     case Style:
-        delete static_cast<StyleRule*>(this);
+        delete toStyleRule(this);
         return;
     case Page:
         delete static_cast<StyleRulePage*>(this);
@@ -143,7 +143,7 @@ PassRefPtr<CSSRule> StyleRuleBase::createCSSOMWrapper(CSSStyleSheet* parentSheet
     StyleRuleBase* self = const_cast<StyleRuleBase*>(this);
     switch (type()) {
     case Style:
-        rule = CSSStyleRule::create(static_cast<StyleRule*>(self), parentSheet);
+        rule = CSSStyleRule::create(toStyleRule(self), parentSheet);
         break;
     case Page:
         rule = CSSPageRule::create(static_cast<StyleRulePage*>(self), parentSheet);