Auto merge of #18508 - mstange:add-fsbgc-system-colors, r=emilio

style: Add system colors from bug 1387594.

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These are the necessary servo changes for https://bugzilla.mozilla.org/show_bug.cgi?id=1387594 .

I'm also re-importing the generated Gecko bindings from my object directory:
 - servo/components/style/gecko/generated/structs_debug.rs
 - servo/components/style/gecko/generated/structs_release.rs

But the number of changes to those files surprises me.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because they're tested by compiling mozilla-central once the patches from https://bugzilla.mozilla.org/show_bug.cgi?id=1387594 land - without this patch, Firefox won't compile.

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

@@ -40,6 +40,10 @@ pub mod system_colors {
                            -moz-mac-defaultbuttontext -moz-mac-focusring -moz-mac-menuselect
                            -moz-mac-menushadow -moz-mac-menutextdisable -moz-mac-menutextselect
                            -moz-mac-disabledtoolbartext -moz-mac-secondaryhighlight
+                           -moz-mac-vibrancy-light -moz-mac-vibrancy-dark -moz-mac-menupopup
+                           -moz-mac-menuitem -moz-mac-active-menuitem -moz-mac-source-list
+                           -moz-mac-source-list-selection -moz-mac-active-source-list-selection
+                           -moz-mac-tooltip
                            -moz-menuhover -moz-menuhovertext -moz-menubartext -moz-menubarhovertext
                            -moz-oddtreerow -moz-win-mediatext -moz-win-communicationstext
                            -moz-win-accentcolor -moz-win-accentcolortext