[IR] Remove unused Ir.irModule property

It is required for the Native backend refactoring
where `Context` does not contain a reference for any
particular IrModuleFragment.

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

@@ -59,7 +59,6 @@ class JsIrBackendContext(
     val module: ModuleDescriptor,
     override val irBuiltIns: IrBuiltIns,
     val symbolTable: SymbolTable,
-    irModuleFragment: IrModuleFragment,
     val additionalExportedDeclarationNames: Set<FqName>,
     keep: Set<String>,
     override val configuration: CompilerConfiguration, // TODO: remove configuration from backend context
@@ -193,7 +192,7 @@ class JsIrBackendContext(
         .find { it.valueParameters.firstOrNull()?.type?.isFunctionType == true }
         .let { symbolTable.referenceSimpleFunction(it!!) }
 
-    override val ir = object : Ir<JsIrBackendContext>(this, irModuleFragment) {
+    override val ir = object : Ir<JsIrBackendContext>(this) {
         override val symbols = object : Symbols(irBuiltIns, symbolTable) {
             private val context = this@JsIrBackendContext
 

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

@@ -105,7 +105,6 @@ fun compileIr(
         moduleDescriptor,
         irBuiltIns,
         symbolTable,
-        allModules.first(),
         exportedDeclarations,
         keep,
         configuration,

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

@@ -39,7 +39,6 @@ class JsIrCompilerWithIC(
             mainModule.descriptor,
             irBuiltIns,
             symbolTable,
-            mainModule,
             exportedDeclarations,
             keep = emptySet(),
             configuration = configuration,