Plain Css Nesting.Changes

Draft 1.2

• Trigger plain CSS nesting behavior based on the type of the parent rule's stylesheet, so that we don't unexpectedly generate plain-CSS nesting for previously un-nested @import and meta.load-css() rules.

Draft 1.1

• Trigger plain CSS nesting behavior based on the type of a rule's stylesheet, rather than the type of the current stylesheet, so that plain CSS behavior is preserved for nested @import and meta.load-css().

Draft 1

• Initial draft.