--- a/layout/style/ServoCSSPropList.mako.py
+++ b/layout/style/ServoCSSPropList.mako.py
@@ -53,19 +53,16 @@ def is_internal(prop):
     # A property which is not controlled by pref and not enabled in
     # content by default is an internal property.
     if not prop.gecko_pref and not prop.enabled_in_content():
         return True
     # There are some special cases we may want to remove eventually.
     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
 
 def method(prop):
     if prop.name == "float":
         return "CssFloat"
     if prop.name.startswith("-x-"):
         return prop.camel_case[1:]

--- a/layout/style/test/test_non_content_accessible_properties.html
+++ b/layout/style/test/test_non_content_accessible_properties.html
@@ -4,21 +4,19 @@
 <style id="sheet"></style>
 <div></div>
 <script>
 const NON_CONTENT_ACCESSIBLE_PROPERTIES = [
   "-x-span",
   "-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",
   "-moz-math-display",
   "-moz-math-variant",
   "-moz-script-min-size",
   "-moz-font-smoothing-background-color",
   "-moz-min-font-size-ratio",

--- a/servo/components/style/properties/longhand/ui.mako.rs
+++ b/servo/components/style/properties/longhand/ui.mako.rs
@@ -36,45 +36,50 @@
 
 ${helpers.single_keyword("-moz-window-shadow", "none default menu tooltip sheet", products="gecko",
                          gecko_ffi_name="mWindowShadow",
                          gecko_constant_prefix="NS_STYLE_WINDOW_SHADOW",
                          animation_value_type="discrete",
                          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",
     "generics::transform::Transform::none()",
     products="gecko",
     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",
     "computed::TransformOrigin::initial_value()",
     animation_value_type="ComputedValue",
     gecko_ffi_name="mWindowTransformOrigin",
     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.
 ${helpers.predefined_type("-moz-force-broken-image-icon",
                           "MozForceBrokenImageIcon",
                           "computed::MozForceBrokenImageIcon::false_value()",
                           animation_value_type="discrete",
                           products="gecko",