Update runtime files.

runtime/syntax/swiftgyb.vim

@@ -0,0 +1,24 @@
+" This source file is part of the Swift.org open source project
+"
+" Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+" Licensed under Apache License v2.0 with Runtime Library Exception
+"
+" See https://swift.org/LICENSE.txt for license information
+" See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+"
+" Vim syntax file
+" Language: gyb on swift
+"
+" Vim maintainer: Emir SARI <bitigchi@me.com>
+
+runtime! syntax/swift.vim
+unlet b:current_syntax
+
+syn include @Python syntax/python.vim
+syn region pythonCode matchgroup=gybPythonCode start=+^ *%+ end=+$+ contains=@Python keepend
+syn region pythonCode matchgroup=gybPythonCode start=+%{+ end=+}%+ contains=@Python keepend
+syn match gybPythonCode /\${[^}]*}/
+hi def link gybPythonCode CursorLineNr
+
+let b:current_syntax = "swiftgyb"
+