[JS/IR] fix: add ability to render type constraints into TypeScript definitions.

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

@@ -81,7 +81,7 @@ data class ExportedRegularClass(
     val isAbstract: Boolean = false,
     override val superClass: ExportedType? = null,
     override val superInterfaces: List<ExportedType> = emptyList(),
-    val typeParameters: List<String>,
+    val typeParameters: List<ExportedType.TypeParameter>,
     override val members: List<ExportedDeclaration>,
     override val nestedClasses: List<ExportedClass>,
     override val ir: IrClass,

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

@@ -378,7 +378,7 @@ class ExportModelGenerator(
         members: List<ExportedDeclaration>,
         nestedClasses: List<ExportedClass>
     ): ExportedDeclaration {
-        val typeParameters = klass.typeParameters.map { it.name.identifier }
+        val typeParameters = klass.typeParameters.map(::exportTypeParameter)
 
         // TODO: Handle non-exported super types
 

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

@@ -258,7 +258,7 @@ class ExportModelToTsDeclarations {
         }
 
         val renderedTypeParameters = if (typeParameters.isNotEmpty()) {
-            "<" + typeParameters.joinToString(", ") + ">"
+            "<" + typeParameters.joinToString(", ") { it.toTypeScript(indent) } + ">"
         } else {
             ""
         }