gapil/resolver: Improve statement sem<->ast mappings
gapil/resolver: Improve statement sem<->ast mappings

pmuetschard/gapid,google/agi,pmuetschard/gapid,google/gapid,Qining/gapid,google/agi,google/gapid,google/agi,pmuetschard/gapid,google/gapid,google/gapid,google/agi,google/agi,google/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,pmuetschard/gapid,google/agi,Qining/gapid,google/gapid,google/agi,Qining/gapid,google/gapid,google/gapid,Qining/gapid,Qining/gapid,google/agi,pmuetschard/gapid,Qining/gapid