[FIR JS] Create an LT diagnostics runner

js/js.tests/test/org/jetbrains/kotlin/generators/tests/GenerateJsTests.kt

@@ -220,6 +220,15 @@ fun main(args: Array<String>) {
                 )
             }
 
+            testClass<AbstractFirLightTreeJsDiagnosticTest>(suiteTestClassName = "FirLightTreeJsOldFrontendDiagnosticsTestGenerated") {
+                model(
+                    relativeRootPath = "diagnostics/testsWithJsStdLib",
+                    pattern = "^([^_](.+))\\.kt$",
+                    excludedPattern = excludedFirTestdataPattern,
+                    targetBackend = TargetBackend.JS_IR
+                )
+            }
+
             testClass<AbstractFirPsiJsDiagnosticWithBackendTest>(suiteTestClassName = "FirPsiJsOldFrontendDiagnosticsWithBackendTestGenerated") {
                 model(
                     relativeRootPath = "diagnostics/testsWithJsStdLibAndBackendCompilation",

js/js.tests/test/org/jetbrains/kotlin/js/test/fir/AbstractFirPsiJsDiagnosticTest.kt

@@ -101,5 +101,6 @@ abstract class AbstractFirJsDiagnosticWithBackendTestBase(parser: FirParser) : A
 }
 
 abstract class AbstractFirPsiJsDiagnosticTest : AbstractFirJsDiagnosticTestBase(FirParser.Psi)
+abstract class AbstractFirLightTreeJsDiagnosticTest : AbstractFirJsDiagnosticTestBase(FirParser.LightTree)
 
 abstract class AbstractFirPsiJsDiagnosticWithBackendTest : AbstractFirJsDiagnosticWithBackendTestBase(FirParser.Psi)