* origin/topic/vern/when-lambda:
explicitly provide the frame for evaluating a "when" timeout expression
attempt to make "when" btest deterministic
tests for new "when" semantics/errors
update existing test suite usage of "when" statements to include captures
update uses of "when" in base scripts to include captures
captures for "when" statements update Triggers to IntrusivePtr's and simpler AST traversal introduce IDSet type, migrate associated "ID*" types to "const ID*"
logic (other than in profiling) for assignments that yield separate values
option for internal use to mark a function type as allowing non-expression returns
removed some now-obsolete profiling functionality
minor commenting clarifications
3d9d6e953b