Bug 1304302 part 2 - Some small fixes. r=heycam

MozReview-Commit-ID: 7rnl4wkMorC

layout/style/Loader.cpp

@@ -1121,7 +1121,7 @@ Loader::CreateSheet(nsIURI* aURI,
       // Then our per-document complete sheets.
       URIPrincipalReferrerPolicyAndCORSModeHashKey key(aURI, aLoaderPrincipal, aCORSMode, aReferrerPolicy);
 
-      StyleSheetHandle completeSheet;
+      StyleSheetHandle completeSheet = nullptr;
       mSheets->mCompleteSheets.Get(&key, &completeSheet);
       sheet = completeSheet;
       LOG(("  From completed: %p", sheet->AsVoidPtr()));