veyron2/vdl/gen: Changed javascript generation to work in node or browser.
veyron2/vdl/gen: Changed javascript generation to work in node or
browser.

Change-Id: I0d7abd14f37edb6181112f90228926deb7d2f08d

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23