IR: use DescriptorBySignatureFinder in DeclarationStubGenerator

Duplicating code that was used for the same purpose in
DeclarationStubGenerator is removed.

compiler/tests-common/tests/org/jetbrains/kotlin/ir/AbstractIrGeneratorTestCase.kt

@@ -168,7 +168,9 @@ abstract class AbstractIrGeneratorTestCase : CodegenTestCase() {
                 generatorExtensions
             )
             val irProviders = generateTypicalIrProviderList(
-                moduleDescriptor, context.irBuiltIns, context.symbolTable, extensions = generatorExtensions
+                moduleDescriptor, context.irBuiltIns, context.symbolTable,
+                extensions = generatorExtensions,
+                mangler = JsManglerDesc,
             )
             return psi2ir.generateModuleFragment(context, ktFilesToAnalyze, irProviders, emptyList())
         }

compiler/tests-common/tests/org/jetbrains/kotlin/ir/AbstractIrTextTestCase.kt

@@ -57,7 +57,8 @@ abstract class AbstractIrTextTestCase : AbstractIrGeneratorTestCase() {
         val stubGenerator = DeclarationStubGeneratorImpl(
             irModule.descriptor,
             SymbolTable(signaturer, IrFactoryImpl), // TODO
-            irModule.irBuiltins
+            irModule.irBuiltins,
+            mangler,
         )
 
         val path = wholeFile.path