Support predefined types in type predicates

In `function (): object {...}` object is a predefined type, but
in `function (object: any): object is foo{}` object is now
a regular identifier. The previous grammar was not able
to parse the second example, probably because when the parsers
sees the second ':' for the return type, the contextual lexual
does not know yet if it's a type predicate or predefined type, so
it accepts 'object' as a predefined type and only fail later when
it sees 'is'.

test plan:

I tried in astexplorer.net and the second example is valid typescript
code (sadly).

Author: aryx

common/corpus/types.txt

@@ -876,6 +876,30 @@ function isT(t: T): t is T {
         (type_identifier)))
     (statement_block (return_statement (true)))))
 
+==================================
+Type predicate and predefined types
+==================================
+
+function isFish(pet: Fish): pet is Fish {
+}
+
+function isFish(object: Fish): object is Fish {
+}
+
+---
+(program
+  (function_declaration (identifier)
+    (formal_parameters
+       (required_parameter (identifier) (type_annotation (type_identifier))))
+    (type_predicate_annotation (type_predicate (identifier) (type_identifier)))
+    (statement_block))
+  (function_declaration (identifier)
+    (formal_parameters
+      (required_parameter (identifier) (type_annotation (type_identifier))))
+    (type_predicate_annotation (type_predicate (identifier) (type_identifier)))
+    (statement_block))
+)
+
 ==================================
 Read-only arrays
 ==================================

common/define-grammar.js

@@ -686,7 +686,16 @@ module.exports = function defineGrammar(dialect) {
       )),
 
       type_predicate: $ => seq(
-        field('name', choice($.identifier, $.this)),
+          field('name', choice(
+	      $.identifier,
+	      $.this,
+	      // Sometimes tree-sitter contextual lexing is not good enough to know
+	      // that 'object' in ':object is foo' is really an identifier and not
+	      // a predefined_type, so we must explicitely list all possibilities.
+	      // TODO: should we use '_reserved_identifier'? Should all the element in
+	      // 'predefined_type' be added to '_reserved_identifier'?
+	      alias($.predefined_type, $.identifier)
+	  )),
         'is',
         field('type', $._type)
       ),