Bug 1467536: followup: Use a more specific capture for the lambda. r=xidorn

MozReview-Commit-ID: 8ykWCzCO0yw

layout/style/nsComputedDOMStyle.cpp

@@ -452,7 +452,7 @@ nsComputedDOMStyle::GetPropertyValue(const nsAString& aPropertyName,
     return NS_ERROR_NOT_AVAILABLE;
   }
 
-  auto cleanup = mozilla::MakeScopeExit([&] {
+  auto cleanup = mozilla::MakeScopeExit([this] {
     ClearCurrentStyleSources();
   });