diff --git a/layout/style/ServoCSSPropList.mako.py b/layout/style/ServoCSSPropList.mako.py
index 4fdce213bc74..659f0ffa01a5 100644
--- a/layout/style/ServoCSSPropList.mako.py
+++ b/layout/style/ServoCSSPropList.mako.py
@@ -58,9 +58,6 @@ def is_internal(prop):
     OTHER_INTERNALS = [
         "-moz-context-properties",
         "-moz-control-character-visibility",
-        "-moz-window-opacity",
-        "-moz-window-transform",
-        "-moz-window-transform-origin",
     ]
     return prop.name in OTHER_INTERNALS
 
diff --git a/layout/style/test/test_non_content_accessible_properties.html b/layout/style/test/test_non_content_accessible_properties.html
index 9018246d3040..a9c049ed456a 100644
--- a/layout/style/test/test_non_content_accessible_properties.html
+++ b/layout/style/test/test_non_content_accessible_properties.html
@@ -9,11 +9,9 @@ const NON_CONTENT_ACCESSIBLE_PROPERTIES = [
   "-x-lang",
   "-x-text-zoom",
   "-moz-window-shadow",
-  // FIXME(bug 1419695): These should be hidden, but Gecko would refuse to
-  // transition them. We need to fix that.
-  // "-moz-window-opacity",
-  // "-moz-window-transform",
-  // "-moz-window-transform-origin",
+  "-moz-window-opacity",
+  "-moz-window-transform",
+  "-moz-window-transform-origin",
   "-moz-top-layer",
   "-moz-script-size-multiplier",
   "-moz-script-level",
diff --git a/servo/components/style/properties/longhand/ui.mako.rs b/servo/components/style/properties/longhand/ui.mako.rs
index 683a8967ea3a..13a940b2b960 100644
--- a/servo/components/style/properties/longhand/ui.mako.rs
+++ b/servo/components/style/properties/longhand/ui.mako.rs
@@ -41,13 +41,17 @@ ${helpers.single_keyword("-moz-window-shadow", "none default menu tooltip sheet"
                          enabled_in="chrome",
                          spec="None (Nonstandard internal property)")}
 
-// TODO(bug 1419695) This should be hidden from content.
-${helpers.predefined_type("-moz-window-opacity", "Opacity", "1.0", products="gecko",
-                          gecko_ffi_name="mWindowOpacity",
-                          animation_value_type="ComputedValue",
-                          spec="None (Nonstandard internal property)")}
+${helpers.predefined_type(
+    "-moz-window-opacity",
+    "Opacity",
+    "1.0",
+    products="gecko",
+    gecko_ffi_name="mWindowOpacity",
+    animation_value_type="ComputedValue",
+    spec="None (Nonstandard internal property)",
+    enabled_in="chrome",
+)}
 
-// TODO(bug 1419695) This should be hidden from content.
 ${helpers.predefined_type(
     "-moz-window-transform",
     "Transform",
@@ -56,10 +60,10 @@ ${helpers.predefined_type(
     gecko_ffi_name="mSpecifiedWindowTransform",
     flags="GETCS_NEEDS_LAYOUT_FLUSH",
     animation_value_type="ComputedValue",
-    spec="None (Nonstandard internal property)"
+    spec="None (Nonstandard internal property)",
+    enabled_in="chrome",
 )}
 
-// TODO(bug 1419695) This should be hidden from content.
 ${helpers.predefined_type(
     "-moz-window-transform-origin",
     "TransformOrigin",
@@ -69,7 +73,8 @@ ${helpers.predefined_type(
     products="gecko",
     boxed=True,
     flags="GETCS_NEEDS_LAYOUT_FLUSH",
-    spec="None (Nonstandard internal property)"
+    spec="None (Nonstandard internal property)",
+    enabled_in="chrome",
 )}
 
 // TODO(emilio): Probably also should be hidden from content.