Bug 1515946 - Let scroll anchoring ride the trains on everything except Fennec. r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D17086

--HG--
extra : moz-landing-system : lando

mobile/android/app/geckoview-prefs.js

@@ -35,5 +35,9 @@ pref("dom.push.enabled", false);
 // in gfxPrefs.h from whether or not WR is enabled.
 pref("layout.scroll.root-frame-containers", 2);
 
+// Scroll anchoring is disabled in Fennec but not GeckoView because of
+// regressions involving the dynamic toolbar. See bug 1520666 for more details.
+pref("layout.css.scroll-anchoring.enabled", true);
+
 // Inherit locale from the OS, used for multi-locale builds
 pref("intl.locale.requested", "");

modules/libpref/init/StaticPrefList.h

@@ -883,7 +883,7 @@ VARCACHE_PREF(
 )
 
 // Pref to control enabling scroll anchoring.
-#ifdef NIGHTLY_BUILD
+#ifndef ANDROID
 #define PREF_VALUE true
 #else
 #define PREF_VALUE false