Bug 1437623 part 2: (layout/base) Add missing includes/namespaces to preemptively fix unified bustage. r=mats

MozReview-Commit-ID: G4ufWWf9qRC

layout/base/nsStyleSheetService.cpp

@@ -28,6 +28,7 @@
 #include "nsIConsoleService.h"
 #include "nsIObserverService.h"
 #include "nsLayoutStatics.h"
+#include "nsLayoutUtils.h"
 
 using namespace mozilla;