--- a/layout/style/GroupRule.cpp
+++ b/layout/style/GroupRule.cpp
@@ -361,29 +361,11 @@ GroupRule::SizeOfExcludingThis(MallocSiz
   }
 
   // Measurement of the following members may be added later if DMD finds it is
   // worthwhile:
   // - mRuleCollection
   return n;
 }
 
-// -------------------------------
-// ConditionRule
-//
-
-ConditionRule::ConditionRule(uint32_t aLineNumber, uint32_t aColumnNumber)
-  : GroupRule(aLineNumber, aColumnNumber)
-{
-}
-
-ConditionRule::ConditionRule(const ConditionRule& aCopy)
-  : GroupRule(aCopy)
-{
-}
-
-ConditionRule::~ConditionRule()
-{
-}
-
 
 } // namespace css
 } // namespace mozill

--- a/layout/style/GroupRule.h
+++ b/layout/style/GroupRule.h
@@ -96,22 +96,19 @@ protected:
   IncrementalClearCOMRuleArray mRules;
   RefPtr<GroupRuleRuleList> mRuleCollection; // lazily constructed
 };
 
 // Implementation of WebIDL CSSConditionRule.
 class ConditionRule : public GroupRule
 {
 protected:
-  ConditionRule(uint32_t aLineNumber, uint32_t aColumnNumber);
-  ConditionRule(const ConditionRule& aCopy);
-  virtual ~ConditionRule();
+  using GroupRule::GroupRule;
 
 public:
-
   // GetConditionText signature matches nsIDOMCSSConditionRule, so subclasses
   // can implement this easily.  The implementations should never return
   // anything other than NS_OK.
   NS_IMETHOD GetConditionText(nsAString& aConditionText) = 0;
   virtual void SetConditionText(const nsAString& aConditionText,
                                 ErrorResult& aRv) = 0;
 };