[JS] Don't produce metadata-only (IR-less) KLIBs in JS

The scenario when JS source code is shared between a few JS common
source sets is not supported in Kotlin Multiplatform.

^KT-61136

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/klib.kt

@@ -98,9 +98,6 @@ val KotlinLibrary.serializedKlibFingerprint: SerializedKlibFingerprint?
 private val CompilerConfiguration.metadataVersion
     get() = get(CommonConfigurationKeys.METADATA_VERSION) as? KlibMetadataVersion ?: KlibMetadataVersion.INSTANCE
 
-private val CompilerConfiguration.expectActualLinker: Boolean
-    get() = get(CommonConfigurationKeys.EXPECT_ACTUAL_LINKER) ?: false
-
 private val SerializedIrFile.fileMetadata: ByteArray
     get() = backendSpecificMetadata ?: error("Expect file caches to have backendSpecificMetadata, but '$path' doesn't")
 
@@ -838,7 +835,6 @@ fun KlibMetadataIncrementalSerializer(configuration: CompilerConfiguration, proj
         metadataVersion = configuration.metadataVersion,
         project = project,
         exportKDoc = false,
-        skipExpects = !configuration.expectActualLinker,
         allowErrorTypes = allowErrors
     )