--- a/layout/style/Loader.cpp
+++ b/layout/style/Loader.cpp
@@ -1273,17 +1273,17 @@ Loader::CreateSheet(nsIURI* aURI,
  * the sheet had "alternate" in its rel.
  */
 void
 Loader::PrepareSheet(StyleSheet* aSheet,
                      const nsSubstring& aTitle,
                      const nsSubstring& aMediaString,
                      nsMediaList* aMediaList,
                      Element* aScopeElement,
-                     bool isAlternate)
+                     bool aIsAlternate)
 {
   NS_PRECONDITION(aSheet, "Must have a sheet!");
 
   // XXXheycam Need to set media, title, etc. on ServoStyleSheets.
   if (aSheet->IsServo()) {
     NS_WARNING("stylo: should set metadata on ServoStyleSheets. See bug 1290209.");
     return;
   }
@@ -1302,17 +1302,17 @@ Loader::PrepareSheet(StyleSheet* aSheet,
     // We have aMediaString only when linked from link elements, style
     // elements, or PIs, so pass true.
     mediumParser.ParseMediaList(aMediaString, nullptr, 0, mediaList);
   }
 
   aSheet->SetMedia(mediaList);
 
   aSheet->SetTitle(aTitle);
-  sheet->SetEnabled(!isAlternate);
+  sheet->SetEnabled(!aIsAlternate);
   sheet->SetScopeElement(aScopeElement);
 }
 
 /**
  * InsertSheetInDoc handles ordering of sheets in the document.  Here
  * we have two types of sheets -- those with linking elements and
  * those without.  The latter are loaded by Link: headers.
  * The following constraints are observed:

--- a/layout/style/Loader.h
+++ b/layout/style/Loader.h
@@ -469,23 +469,23 @@ private:
                        bool aHasAlternateRel,
                        const nsAString& aTitle,
                        StyleSheetState& aSheetState,
                        bool *aIsAlternate,
                        RefPtr<StyleSheet>* aSheet);
 
   // Pass in either a media string or the nsMediaList from the
   // CSSParser.  Don't pass both.
-  // This method will set the sheet's enabled state based on isAlternate
+  // This method will set the sheet's enabled state based on aIsAlternate
   void PrepareSheet(StyleSheet* aSheet,
                     const nsAString& aTitle,
                     const nsAString& aMediaString,
                     nsMediaList* aMediaList,
                     dom::Element* aScopeElement,
-                    bool isAlternate);
+                    bool aIsAlternate);
 
   nsresult InsertSheetInDoc(StyleSheet* aSheet,
                             nsIContent* aLinkingContent,
                             nsIDocument* aDocument);
 
   nsresult InsertChildSheet(StyleSheet* aSheet,
                             StyleSheet* aParentSheet,
                             ImportRule* aGeckoParentRule,