[JS IR] save the desired JS output file name in the klib.

This is only usedful for code splitting. The output .js file name
is provided by the build system during the module compilation.
It is desirable to keep the .js output file names same as in old BE,
but calculating those name during the klib -> js phase is tricky.

Thus the desired names are saved in the klib, and used later on.

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

@@ -54,7 +54,7 @@ fun compile(
     propertyLazyInitialization: Boolean,
     legacyPropertyAccess: Boolean = false,
 ): CompilerResult {
-    val (moduleFragment: IrModuleFragment, dependencyModules, irBuiltIns, symbolTable, deserializer) =
+    val (moduleFragment: IrModuleFragment, dependencyModules, irBuiltIns, symbolTable, deserializer, moduleToName) =
         loadIr(project, mainModule, analyzer, configuration, allDependencies, friendDependencies, irFactory)
 
     val moduleDescriptor = moduleFragment.descriptor
@@ -109,7 +109,8 @@ fun compile(
             fullJs = true,
             dceJs = false,
             multiModule = multiModule,
-            relativeRequirePath = relativeRequirePath
+            relativeRequirePath = relativeRequirePath,
+            moduleToName = moduleToName,
         )
         return transformer.generateModule(allModules)
     } else {
@@ -120,7 +121,8 @@ fun compile(
             fullJs = generateFullJs,
             dceJs = generateDceJs,
             multiModule = multiModule,
-            relativeRequirePath = relativeRequirePath
+            relativeRequirePath = relativeRequirePath,
+            moduleToName = moduleToName,
         )
         return transformer.generateModule(allModules)
     }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrModuleToJsTransformer.kt

@@ -31,7 +31,8 @@ class IrModuleToJsTransformer(
     private val fullJs: Boolean = true,
     private val dceJs: Boolean = false,
     private val multiModule: Boolean = false,
-    private val relativeRequirePath: Boolean = false
+    private val relativeRequirePath: Boolean = false,
+    private val moduleToName: Map<IrModuleFragment, String> = emptyMap()
 ) {
     private val generateRegionComments = backendContext.configuration.getBoolean(JSConfigurationKeys.GENERATE_REGION_COMMENTS)
 
@@ -91,7 +92,7 @@ class IrModuleToJsTransformer(
             )
 
             val dependencies = others.mapIndexed { index, module ->
-                val moduleName = sanitizeName(module.safeName)
+                val moduleName = moduleToName[module] ?: sanitizeName(module.safeName)
 
                 val exportedDeclarations = ExportModelGenerator(backendContext).let { module.files.flatMap { file -> it.generateExport(file) } }
 
@@ -206,7 +207,7 @@ class IrModuleToJsTransformer(
             }
 
             val moduleName = declareFreshGlobal(module.safeName)
-            modules += JsImportedModule(moduleName.ident, moduleName, moduleName.makeRef(), relativeRequirePath)
+            modules += JsImportedModule(moduleToName[module] ?: moduleName.ident, moduleName, moduleName.makeRef(), relativeRequirePath)
 
             names.forEach {
                 imports += JsVars(JsVars.JsVar(JsName(it), JsNameRef(it, JsNameRef("\$crossModule\$", moduleName.makeRef()))))