[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/testsWithStdLib/experimental/errors.fir.kt

@@ -0,0 +1,26 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental
+annotation class E
+
+open class Base {
+    @E
+    open fun foo() {}
+}
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+class Derived : Base() {
+    override fun foo() {}
+}
+
+fun test(b: Base) {
+    b.foo()
+}