Generate light classes for single-file facades using PackageCodegen.

compiler/backend/src/org/jetbrains/kotlin/codegen/MultifileClassCodegen.kt

@@ -116,8 +116,6 @@ public class MultifileClassCodegen(
             tasks: Map<CallableMemberDescriptor, () -> Unit>,
             partFqNames: List<FqName>
     ) {
-        if (files.size() == 1 && state.classBuilderMode == ClassBuilderMode.LIGHT_CLASSES) return
-
         generateKotlinPackageReflectionField()
         MemberCodegen.generateModuleNameField(state, classBuilder)
 

compiler/backend/src/org/jetbrains/kotlin/codegen/MultifileClassPartCodegen.kt

@@ -43,6 +43,10 @@ public class MultifileClassPartCodegen(
         partContext: FieldOwnerContext<*>,
         state: GenerationState
 ) : MemberCodegen<JetFile>(state, null, partContext, file, v) {
+    override fun generate() {
+        if (state.classBuilderMode == ClassBuilderMode.LIGHT_CLASSES) return
+        super.generate()
+    }
 
     override fun generateDeclaration() {
         v.defineClass(element, Opcodes.V1_6,