Swift: Extend the taint test with WKUserScript.

Author: geoffw0

swift/ql/test/library-tests/dataflow/taint/LocalTaint.expected

@@ -165,4 +165,4 @@
 | url.swift:100:12:100:54 | ...! | url.swift:100:12:100:56 | .standardizedFileURL |
 | url.swift:101:15:101:57 | ...! | url.swift:101:15:101:59 | .user |
 | url.swift:102:15:102:57 | ...! | url.swift:102:15:102:59 | .password |
-| webview.swift:52:11:52:18 | call to source() | webview.swift:52:10:52:41 | .body |
+| webview.swift:77:11:77:18 | call to source() | webview.swift:77:10:77:41 | .body |