Bug 1267890 part 1 - Add @supports -moz-bool-pref() support for stylo. r=emilio

MozReview-Commit-ID: C9Pq2zLLaGp

--HG--
extra : source : b7c8a25d84695de47acda8065b21c0a96759f87b

layout/style/ServoBindings.cpp

@@ -58,6 +58,7 @@
 #include "mozilla/GeckoStyleContext.h"
 #include "mozilla/Keyframe.h"
 #include "mozilla/Mutex.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/ServoElementSnapshot.h"
 #include "mozilla/ServoRestyleManager.h"
 #include "mozilla/SizeOfState.h"
@@ -2832,3 +2833,10 @@ Gecko_GetElementsWithId(const nsIDocument* aDocument, nsAtom* aId)
 
   return aDocument->GetAllElementsForId(nsDependentAtomString(aId));
 }
+
+bool
+Gecko_GetBoolPrefValue(const char* aPrefName)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  return Preferences::GetBool(aPrefName);
+}

layout/style/ServoBindings.h

@@ -715,6 +715,10 @@ const nsTArray<mozilla::dom::Element*>* Gecko_GetElementsWithId(
     const nsIDocument* aDocument,
     nsAtom* aId);
 
+// Check the value of the given bool preference. The pref name needs to
+// be null-terminated.
+bool Gecko_GetBoolPrefValue(const char* pref_name);
+
 } // extern "C"
 
 #endif // mozilla_ServoBindings_h