Fixes and improvements for UglifyJS->SM AST conversion.
Fixes and improvements for UglifyJS->SM AST conversion.

* Explicitly forbidden multiple catch clauses as SM-specific feature.
* Simplified describing of UglifyJS->Mozilla AST conversion rules.
* Moved alias rules to single place.
* Removed usage of dynamic type bindings in generated code (speed-up).

microlv/UglifyJS2,istr/UglifyJS2,dabretin/UglifyJS2,sielay/UglifyJS2,sebmck/UglifyJS2,eth-srl/UnuglifyJS,butchi/codedecodeJS,GerHobbelt/UglifyJS2,TurkeyFried/uglifyjs2-dist,avdg/UglifyJS2,davidbau/UglifyJS2,hychen/UglifyJS2,butchi/decodecodeJS,vjeux/UglifyJS2,Jeremy017/UglifyJS2,githuboflee/first,jchbh-duplicate/UglifyJS2,kemitchell/UglifyJS2,VIVEKLUCKY1848/UglifyJS2,supriyantomaftuh/UglifyJS2,kittens/UglifyJS2,HankMcCoy/UglifyJS2,beni55/UnuglifyJS,rvanvelzen/UglifyJS2,digitalloggers/UglifyJS2,hxford/UglifyJS2,shanaithal/UglifyJS2,SpainTrain/UglifyJS2,eth-srl/UnuglifyJS,shelsonjava/UglifyJS2,beni55/UnuglifyJS,Venima/Test