wabt

8761c560 - Add interpreter support for the exception handling proposal (#1749)

Add interpreter support for the exception handling proposal (#1749) Details about the implementation approach: * Try blocks generate metadata tracking the instruction ranges for the handlers and which exception tags are handled (or if a `catch_all` is present). The metadata is stored in a function's `FuncDesc`, and is transferred into the `Frame` when a function call is executed. * The stack is unwound when a `throw` is executed. This unwinding also handles tag dispatch to the appropriate catch. The metadata to find the matching handler is looked up in the call `Frame` stack. * If a `try-delegate` is present, it is used in the stack unwinding process to skip over to the relevant handler. * A separate `exceptions_` stack in call frames tracks caught exceptions that can be accessed via a `rethrow`. The stack is popped on exit from a try block or when exiting via control instructions like `br`. * Because stack unwinding relies on finding metadata in the call frame, `return_call` needs to be modified slightly to adjust the current frame when executing the call, rather than re-using the frame completely as-is.