dd5a5ebdbc
The Wasm translation handles unreachable code sections specially, skipping ops until the end of a block and a control-flow merger at which code becomes reachable again. Unfortunately, while the ordinary else-op handler properly sets up the value stack for the else-branch with the parameters to the if/else, the unreachable-case else-op handler did not. This resulted in a bad translation and CLIF type error despite valid Wasm. Found via fuzzing by :decoder in https://bugzilla.mozilla.org/show_bug.cgi?id=1657895.