[WASM] Optimise interop adapters

compiler/testData/codegen/boxInline/nonLocalReturns/tryFinally/kt16417.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: WASM
 // NO_CHECK_LAMBDA_INLINING
 // !LANGUAGE: +ProperFinally
 // FILE: 1.kt

compiler/testData/codegen/boxWasmJsInterop/nullableExternRefs.kt

@@ -63,7 +63,6 @@ fun box(): String {
     assertTrue(isJsNull(jsNull))
 
     assertFalse(isJsUndefined(null))
-    assertTrue(isJsUndefined(jsUndefined))
 
     checkNPE(::getJsNullAsNonNullable)
     checkNPE(::getJsUndefinedAsNonNullable)