Allow goto-definition to work for named fields in struct initializer

Now goto definition should work when done on a named field in a struct
initializer.

crates/ra_ide_api/src/marks.rs

@@ -2,6 +2,7 @@ test_utils::marks!(
     inserts_parens_for_function_calls
     goto_definition_works_for_methods
     goto_definition_works_for_fields
+    goto_definition_works_for_named_fields
     call_info_bad_offset
     dont_complete_current_use
 );