When exiting a scope, dependent type annotations should no longer refer to its variables

Consider the following code:

{
  int a = 0;

  {
    int b = ...;
    a = b-1;
    // `a` now has type @LessThan("b").  This is fine.
  }

  // BUG: `a` still has type LessThan("b").

  {
    int b = ...
    // `a` still has type LessThan("b") here, which might not be a true relationship!
  }
}

When exiting a scope, type annotations need to be adjusted.

• One approach would be to go through all types in the store and remove references to variables that are going out of scope.
• A simpler approach would be to re-standardize (or re-parse all dependent type Java expressions), and drop any such that yields an error.

Start with the scope-exit handling and type store described in the issue, then reproduce the nested-scope example. The work is done when dependent type annotations no longer refer to variables that have left scope, including preventing the later block from reusing the stale relationship.