The negative lookbehind in DYNAMIC and in the dynamic branch of IMPORT excluded any dot
before `import`. That also skipped the last dot of the spread punctuator, so
`${({...import('../x.mjs')})}` returned [] for an existing, a missing and an outside
target, and `{...import(name)}` in plain code was neither returned nor refused.
Both patterns now share one fragment: a word character or $ before `import`, or a single
dot (x.import, x?.import), makes it a property call; a dot that follows another dot ends a
spread and does not exclude it. `1..import(` is read as an import too, which errs toward
refusal; the header names it.
Tests: a spread inside a substitution refuses for an existing, a missing and an outside
target and for array spread; a spread in plain code is returned, reaches the target
checks, and is refused when its argument is not a plain string; x.import and x?.import
stay property calls in plain code and in a substitution.
jason.woltje
180fb8ab00