Disable align-items in geckolib.

components/style/properties/longhand/position.mako.rs

@@ -77,11 +77,14 @@ ${helpers.single_keyword("justify-content", "flex-start flex-end center space-be
                          products="servo",
                          animatable=False)}
 
+// FIXME(heycam): Disable align-items in geckolib since we don't support the Gecko initial value
+// 'normal' yet.
 ${helpers.single_keyword("align-items", "stretch flex-start flex-end center baseline",
                          experimental=True,
                          need_clone=True,
                          gecko_constant_prefix="NS_STYLE_ALIGN",
-                         animatable=False)}
+                         animatable=False,
+                         products="servo")}
 
 ${helpers.single_keyword("align-content", "stretch flex-start flex-end center space-between space-around",
                          experimental=True,

components/style/properties/properties.mako.rs

@@ -1921,6 +1921,7 @@ pub fn cascade<C: ComputedValues>(
         }
     }
 
+    % if "align-items" in data.longhands_by_name:
     {
         use self::style_struct_traits::Position;
         use computed_values::align_self::T as align_self;
@@ -1937,6 +1938,7 @@ pub fn cascade<C: ComputedValues>(
             style.mutate_position().set_align_self(self_align);
         }
     }
+    % endif
 
     // The initial value of border-*-width may be changed at computed value time.
     % for side in ["top", "right", "bottom", "left"]: