Fine. Link tokens after reading nodes from binary.

`ManifestNode.encode` relies on being able to iterate over tokens of the AST node. And if the default value of a formal parameter of a `FunctionType` that came from summary does not have tokens linked, this causes an exception.

Bug: #62202
Change-Id: I0156dfd935cc9b4fa7ec51b417647f455fa68a61
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/466920
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov