Editorial: Clarify note re parsing the same string multiple times

[jmdyck]

... which was the subject of issue #1484.

This is basically @allenwb's suggested wording from
#1484 (comment)

The example string-to-be-eval'ed isn't one for which the distinctness of parse trees actually matters. Are there any simple cases for which it does?

[gibson042]

The example string-to-be-eval'ed isn't one for which the distinctness of parse trees actually matters. Are there any simple cases for which it does?

Since tagged template literals expose parse node identity (cf. #890), I would try to use them. Examples (condensed into single-expression forms):

• [0, 1].map(_ => (id => id)``).reduce((a, b) => a === b) === true
  vs.
  [0, 1].map(_ => eval("(id => id)``")).reduce((a, b) => a === b) === false
• [0, 1].map((function(){ const id = (id => id)``, isUnique = !this.has(id); this.add(id); return isUnique }).bind(new WeakSet())).every(isUnique => isUnique) === false
  vs.
  [0, 1].map((function(){ const id = eval("(id => id)``"), isUnique = !this.has(id); this.add(id); return isUnique }).bind(new WeakSet())).every(isUnique => isUnique) === true

[jmdyck]

Hm. This is just a Note in an introductory clause, so I'm not sure it should rely on the reader understanding template literals.

Mind you, an example in the Template Literals clause seems like a good idea. Maybe in GetTemplateObject: it has the "is the same Parse Node" test, so a Note could explain the implications of that.

[littledan]

This seems appropriate for the template caching semantics.