8aa23125bb
Re-enable Emscripten's exception handling support Passes LLVM codegen and Emscripten link-time flags for exception handling if and only if the panic strategy is `unwind`. Sets the default panic strategy for Emscripten targets to `unwind`. Re-enables tests that depend on unwinding support for Emscripten, including `should_panic` tests. r? @alexcrichton