[WASM] Revert NeedsThunk patch for thin to thick

Author: kateinoigakukun

lib/SIL/IR/TypeLowering.cpp

@@ -2885,23 +2885,10 @@ TypeConverter::checkFunctionForABIDifferences(SILModule &M,
       return ABIDifference::NeedsThunk;
   }
 
-  // There is no ABI compatibility between non-throws and throws on WebAssembly,
-  // so need thunk.
-  if (M.getASTContext().LangOpts.Target.isOSBinFormatWasm()) {
-    if (!fnTy1->hasErrorResult() && fnTy2->hasErrorResult()) {
-      return ABIDifference::NeedsThunk;
-    }
-  }
-
   auto rep1 = fnTy1->getRepresentation(), rep2 = fnTy2->getRepresentation();
   if (rep1 != rep2) {
     if (rep1 == SILFunctionTypeRepresentation::Thin &&
         rep2 == SILFunctionTypeRepresentation::Thick) {
-      // There is no ABI compatibility between thin and thick on WebAssembly,
-      // so need thunk.
-      if (M.getASTContext().LangOpts.Target.isOSBinFormatWasm()) {
-        return ABIDifference::NeedsThunk;
-      }
       if (DifferentFunctionTypesHaveDifferentRepresentation) {
         // FIXME: check whether the representations are compatible modulo
         // context