LibWeb: Manually convert the js bigint to a wasm i64 value

SignedBigInteger::export() generates sign-magnitude, but the native i64
type uses 2's comp, make this work by exporting it as unsigned and
tweaking the sign later.

1 files changed, 5 insertions, 4 deletions

diff --git a/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp b/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
index 8398c8afab..d3be78d352 100644
--- a/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
+++ b/Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp
@@ -374,10 +374,11 @@ Optional<Wasm::Value> to_webassembly_value(JS::Value value, const Wasm::ValueTyp
         if (vm.exception())
             return {};
         auto value = bigint->big_integer().divided_by(two_64).remainder;
-        VERIFY(value.trimmed_length() <= 2);
-        BigEndian<i64> integer { 0 };
-        value.export_data({ &integer, 2 });
-        return Wasm::Value { static_cast<i64>(integer) };
+        VERIFY(value.unsigned_value().trimmed_length() <= 2);
+        i64 integer = static_cast<i64>(value.unsigned_value().to_u64());
+        if (value.is_negative())
+            integer = -integer;
+        return Wasm::Value { integer };
     }
     case Wasm::ValueType::I32: {
         auto _i32 = value.to_i32(global_object);