WebComment: fix detection of restricted reviews

• Fix detection of whether a review is restricted or public, making the failed web test case to work again.

• Note that the bug was due to x and y or z' technique that is dangerous to use when y may be false, such as empty string. It is safer instead to use (x and [y] or [z])[0]' technique because `[y]' is always true regardless of the value of y. However, the present fix commits the simple, more readable, and less error-prone if/else alternative.