Eval Rewriting + Scope Fix

[ikreymer]

Description

An alternate fix to #663 that removes the WB_wombat_ prefix and instead overrides non-top-level with self.eval.
The proxy in wombat.js intercepts eval() on the object and returns a version that has rewriting enabled.

This is possible since:

a = eval
a(...)

and

a.= self.eval
a(...)

are equivalent in that the eval is run in the global scope, but, the latter allows for interception of eval by the object proxy.

Also: wrapping injected let vars in separate anonymous scope, as suggested in webrecorder/wombat#72

Motivation and Context

Provides a fix for #663 and avoids the false positive introduced in #664.
(Note: still small chance of issue if self is redefined, can revisit if real-world examples come up).

Screenshots (if appropriate):

Types of changes

• Replay fix (fixes a replay specific issue)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added or updated tests to cover my changes.
• All new and existing tests passed.