add src/ component to VDLPATH
add src/ component to VDLPATH

Addresses https://github.com/vanadium/issues/issues/145.

MultiPart: 4/6
Change-Id: Ia4b1b992f4001a0f22f5691dda60501e5c88bec9

vanadium/js,vanadium/js,vanadium/js,vanadium/js