designate type_predicate_annotation as its own rule

Author: resolritter

common/corpus/types.txt

@@ -736,11 +736,11 @@ function isT(t: T): t is T {
       (required_parameter
         (identifier)
         (type_annotation (type_identifier))))
-    (type_predicate
-      (identifier)
-      (type_identifier))
-    (statement_block (return_statement (true))))
-  )
+    (type_predicate_annotation
+      (type_predicate
+        (identifier)
+        (type_identifier)))
+    (statement_block (return_statement (true)))))
 
 ==================================
 Tuple types

common/define-grammar.js

@@ -551,6 +551,10 @@ module.exports = function defineGrammar(dialect) {
         $._type
       ),
 
+      type_predicate_annotation: $ => seq(
+        seq(':', $.type_predicate)
+      ),
+
       type_query: $ => prec(PREC.TYPEOF, seq(
         'typeof',
         choice($.identifier, $.nested_identifier)
@@ -643,7 +647,7 @@ module.exports = function defineGrammar(dialect) {
         field('type_parameters', optional($.type_parameters)),
         field('parameters', $.formal_parameters),
         field('return_type', optional(
-          choice($.type_annotation, $.asserts, seq(':', $.type_predicate))
+          choice($.type_annotation, $.asserts, $.type_predicate_annotation)
         ))
       ),