style: Add a special list for cbindgen types to avoid generating redu…

…ndant rust types.

We will blacklist this type and add a module raw line to map the gecko
type to its rust type (as an alias).

Differential Revision: https://phabricator.services.mozilla.com/D10303

components/style/build_gecko.rs

@@ -392,6 +392,12 @@ mod bindings {
             .handle_str_items("whitelist-vars", |b, item| b.whitelist_var(item))
             .handle_str_items("whitelist-types", |b, item| b.whitelist_type(item))
             .handle_str_items("opaque-types", |b, item| b.opaque_type(item))
+            .handle_table_items("cbindgen-types", |b, item| {
+                let gecko = item["gecko"].as_str().unwrap();
+                let servo = item["servo"].as_str().unwrap();
+                let line = format!("pub use {} as {};", servo, gecko.rsplit("::").next().unwrap());
+                b.blacklist_type(gecko).module_raw_line("root::mozilla", line)
+            })
             .handle_table_items("mapped-generic-types", |builder, item| {
                 let generic = item["generic"].as_bool().unwrap();
                 let gecko = item["gecko"].as_str().unwrap();