After doing some research, I found out that the JavaScript Reserved Words table in the JavaScript Reserved Words article needs to be revised. What I see is a merge between ES2 and ES5. I see "let" in the list, which wasn't added until ES5, yet has no asterisk. I also see keywords that are no longer considered reserved like "int", "long", and "native". So, if the asterisk indicates newly added words, then perhaps we should include a separate indicator for words that are no longer reserved or remove those words from the table entirely.
Here is a table summary of what I found
Sources:
ECMAScript 1 ECMAScript 2 ECMAScript 5 ECMAScript 5.1
ECMAScript 6
Mathias Bynens' Blog