Auto merge of #14978 - shinglyu:inline-flex, r=notriddle

Implemented display: inline-flex

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #14685 (github issue number if applicable).

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- [x] There are tests for these changes
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components/style/properties/properties.mako.rs

@@ -1953,8 +1953,10 @@ pub fn apply_declarations<'a, F, I>(viewport_size: Size2D<Au>,
     let is_item = matches!(context.inherited_style.get_box().clone_display(),
         % if product == "gecko":
         computed_values::display::T::grid |
+        computed_values::display::T::inline_grid |
         % endif
-        computed_values::display::T::flex);
+        computed_values::display::T::flex |
+        computed_values::display::T::inline_flex);
     let (blockify_root, blockify_item) = match flags.contains(SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP) {
         false => (is_root_element, is_item),
         true => (false, false),