[Parse] Gardening: remove unused function

Remove 2 convenient functions:
* parseTypeSimple()
* parseTypeSimpleOrComposition()

Author: rintaro

include/swift/Parse/Parser.h

@@ -933,12 +933,10 @@ class Parser {
                                    bool HandleCodeCompletion = true,
                                    bool IsSILFuncDecl = false);
 
-  ParserResult<TypeRepr> parseTypeSimpleOrComposition();
   ParserResult<TypeRepr>
     parseTypeSimpleOrComposition(Diag<> MessageID,
                                  bool HandleCodeCompletion = true);
 
-  ParserResult<TypeRepr> parseTypeSimple();
   ParserResult<TypeRepr> parseTypeSimple(Diag<> MessageID,
                                          bool HandleCodeCompletion = true);
 

lib/Parse/ParseType.cpp

@@ -157,10 +157,6 @@ LayoutConstraint Parser::parseLayoutConstraint(Identifier LayoutConstraintID) {
                                                alignment, Context);
 }
 
-ParserResult<TypeRepr> Parser::parseTypeSimple() {
-  return parseTypeSimple(diag::expected_type);
-}
-
 /// parseTypeSimple
 ///   type-simple:
 ///     type-identifier
@@ -677,10 +673,6 @@ SyntaxParserResult<TypeSyntax, TypeRepr> Parser::parseTypeIdentifier() {
   return makeSyntaxResult(Status, SyntaxNode, ITR);
 }
 
-ParserResult<TypeRepr> Parser::parseTypeSimpleOrComposition() {
-  return parseTypeSimpleOrComposition(diag::expected_identifier_for_type);
-}
-
 /// parseTypeSimpleOrComposition
 ///
 ///   type-composition: