JS: add metadata for generated continuation classes to properly implement RTTI

compiler/testData/codegen/box/coroutines/instanceOfContinuation.kt

@@ -0,0 +1,30 @@
+// WITH_RUNTIME
+// WITH_REFLECT
+
+class Controller {
+    suspend fun runInstanceOf(x: Continuation<Boolean>) {
+        val y: Any = x
+        x.resume(x is Continuation<*>)
+    }
+
+    suspend fun runCast(x: Continuation<Boolean>) {
+        val y: Any = x
+        x.resume(Continuation::class.isInstance(y as Continuation<*>))
+    }
+}
+
+fun builder(coroutine c: Controller.() -> Continuation<Unit>) {
+    c(Controller()).resume(Unit)
+}
+
+fun box(): String {
+    var result = ""
+
+    builder {
+        result = runInstanceOf().toString() + "," + runCast().toString()
+    }
+
+    if (result != "true,true") return "fail: $result"
+
+    return "OK"
+}