Editorial: remove some unnecessary calls to SameValue

[michaelficarra]

I'm sure there are more of these, these are the ones I noticed today.

[jmdyck]

There's one other place where SameValue is used to compare two Boolean values, in [[IsExtensible]] for a Proxy exotic object.

[jmdyck]

More generally, what's the editorial convention for using SameValue vs is?

E.g., it might be something like...

When comparing two values for (something like) equality:

• If either value might be a specification value, then you can't just use SameValue, because it only accepts ECMAScript language values.
• If both values might be Numbers, then you must use SameValue, because you want the specificity of Number::sameValue.
• Otherwise (i.e., if both values are ECMAScript language values, but not both Numbers), then you could use either SameValue or is, but the preference is to use is.

[michaelficarra]

@jmdyck From #2877:

• use =, ≠, <, ≤, >, and ≥ for mathematical value and bigint comparisons (except in asserts); prefer = over ≠
• use is, is not, <, ≤, >, and ≥ for number comparisons
• use SameValue(..., ...) is *true* for equality comparison of symbols (except well-known) / objects / unknown ECMAScript language values
• use is and is not for equality comparison of all other values, including booleans, strings, well-known symbols, null, undefined, enums, etc; avoid "is different from" or "is the same as"

[michaelficarra]

There's one other place where SameValue is used to compare two Boolean values

Added.