[Chapel Merge] Add control-flow declarations to the spec

Branch: refs/heads/master
Revision: 9dd4d68
Author: vasslitvinov
Log Message:

Merge pull request #17377 from vasslitvinov/ctrl-flow-decls

Add control-flow declarations to the spec

These were previously known as "if-var" and "while-var"
constructs and were implemented in #17047 and #17304.

r: @lydia-duncan

Modified Files:
M doc/rst/language/spec/statements.rst

Compare: https://github.com/chapel-lang/chapel/compare/a50a209d9e44...9dd4d68c8845