* Fixes#8810.
* Prevent a single-line container declaration if it contains a comment
or multiline string.
* If a container declaration cannot be single-line, ensure container
fields are rendered with a trailing comma.
* If `Space.comma` is passed to `renderExpressionComma` or
`renderTokenComma`, and there already exists a comma in the source,
then render one comma instead of two.
a130eac785