Remove syntax highlighting hack for builtin attrs

crates/hir/src/lib.rs

@@ -2028,7 +2028,7 @@ pub struct BuiltinAttr(usize);
 
 impl BuiltinAttr {
     pub(crate) fn by_name(name: &str) -> Option<Self> {
-        // TODO: def maps registered attrs?
+        // FIXME: def maps registered attrs?
         hir_def::builtin_attr::find_builtin_attr_idx(name).map(Self)
     }
 }
@@ -2038,7 +2038,7 @@ pub struct Tool(usize);
 
 impl Tool {
     pub(crate) fn by_name(name: &str) -> Option<Self> {
-        // TODO: def maps registered tools
+        // FIXME: def maps registered tools
         hir_def::builtin_attr::TOOL_MODULES.iter().position(|&tool| tool == name).map(Self)
     }
 }