* 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).
* Added directives recognition in SM AST.
* Moved semi-standard SM `Property` type to separate handler.
* Added `const` recognition from SM AST.
* Removed redundant `this`-as-identifier recognition.
* Removed redundant rules for abstract SM types.
* Described `CatchClause` using string syntax.
* Added support for semi-standard `range` tuple as location source.
* Added back-conversion support (to be improved).
returns an UglifyJS2 AST given a Mozilla AST. Still needs some work to do
(need to create specific nodes like AST_SymbolRef, AST_SymbolLambda
etc. instead of base AST_Symbol, in order for the mangler/compressor to work
properly)
