Clarify the evaluation order for collection literal elements

[eernstg]

The evaluation order for the elements of a collection literal (say, [e1, ...e2, if (b) e3] where e2 is a set) was not mentioned. This PR adds a few words to clarify that evaluation occurs in textual order. The order of evaluation associated with the subsequences with other than a single element is already specified (e.g., the subsequence for a Set spread is obtained by a pseudo-code for-in statement that explicitly states how each object is obtained).

It also corrects a couple of typos where an empty sequence followed by a semicolon was shown as [[;]] rather than [[]];. One more set of typos fixed: \ell changed to \ell_1, four locations, in spec of static analysis of <forElement>.

The wording around "object sequences" is not wonderful, but I'd recommend that we leave it as is for now.

[github-actions]

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