Make second argument to CSSStyleSheet.insertRule() optional again

Source/core/css/CSSStyleSheet.cpp

Index: Source/core/css/CSSStyleSheet.cpp
diff --git a/Source/core/css/CSSStyleSheet.cpp b/Source/core/css/CSSStyleSheet.cpp
index 971b21f8b3f038adbe1a394c5125c4f6fae70019..d8b3bef962f1598041c26f6a8822865f0af39c5a 100644
--- a/Source/core/css/CSSStyleSheet.cpp
+++ b/Source/core/css/CSSStyleSheet.cpp
@@ -35,6 +35,7 @@
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/Node.h"
+#include "core/frame/UseCounter.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "wtf/text/StringBuilder.h"
@@ -320,6 +321,12 @@ unsigned CSSStyleSheet::insertRule(const String& ruleString, unsigned index, Exc
     return index;
 }
 
+unsigned CSSStyleSheet::insertRule(const String& rule, ExceptionState& exceptionState)
+{
+    UseCounter::countDeprecation(activeExecutionContext(), UseCounter::CSSStyleSheetInsertRuleOptionalArg);
+    return insertRule(rule, 0, exceptionState);
+}
+
 void CSSStyleSheet::deleteRule(unsigned index, ExceptionState& exceptionState)
 {
     ASSERT(m_childRuleCSSOMWrappers.isEmpty() || m_childRuleCSSOMWrappers.size() == m_contents->ruleCount());