- empty body
- single `AST_Return`
- single `AST_SimpleStatement`
- avoid `/*#__PURE__*/`
Miscellaneous
- enhance single-use function substitution
fixes#281
Although it would be nice to enforce `AST_Node` cloning during transformation, that ship has sailed a long time ago.
We now get the assigned value when resolving `AST_SymbolRef` instead of `reset_opt_flags()`, which has the added advantage of improved compressor efficiency.
fixes#1787