Don't use multiple tables in wasm-split

Currently, wasm-split will create a second table rather than replacing
the existing one when reftypes is supported (or rather whether a
target_features section is present indicating it's already used).
But the emscripten integration code doesn't currently support this,
and it's not tested anywhere. The existing tests started failing when
Binaryen stopped stripping the features section by default.
(But some users would already be broken by this). For now, removing
this untested behavior is a safe default.

src/ir/module-splitting.cpp

diff --git a/src/ir/module-splitting.cpp b/src/ir/module-splitting.cpp
index f299d7a..ce8bab7 100644
--- a/src/ir/module-splitting.cpp
+++ b/src/ir/module-splitting.cpp
@@ -146,15 +146,6 @@
 }
 
 TableSlotManager::TableSlotManager(Module& module) : module(module) {
-  if (module.features.hasReferenceTypes()) {
-    // Just create a new table to manage all primary-to-secondary calls lazily.
-    // Do not re-use slots for functions that will already be in existing
-    // tables, since that is not correct in the face of table mutations.
-    // TODO: Reduce overhead by creating a separate table for each function type
-    // if WasmGC is enabled.
-    return;
-  }
-
   // TODO: Reject or handle passive element segments
   auto funcref = Type(HeapType::func, Nullable);
   auto it = std::find_if(