Add (trival) AllInFileTransformer to mark trees of files being traced;
 Move the LinearizeTransformer to the beginning of the transformations.
 Guard the QPTreeWriter tracing with the flag from AllInFileTransformer.
 Adjust the doNotTrace markers now that Linearize is applied first.
 Clone the trees before transforming them.
 Change Linearize to deal with references and
 ValueChange to not introduce temps.
sync to traceur compiler
Sync up to changes in traceur Function handling
Wrap comma expr on LHS in paren expression,
since var __qp_33 = a, b; is illegal.
Warn if we have an assignment we cannot trace
with lastChange
FIXME, multiple ValueChangeTransformers are being
run because something is reseting hasValueChangeTransform