Fix isJvmAccessible to handle nested protected Java classes

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -748,13 +748,8 @@ object Erasure {
         // Scala classes are always emitted as public, unless the
         // `private` modifier is used, but a non-private class can never
         // extend a private class, so such a class will never be a cast target.
-        !cls.is(Flags.JavaDefined) || {
-          // We can't rely on `isContainedWith` here because packages are
-          // not nested from the JVM point of view.
-          val boundary = cls.accessBoundary(cls.owner)(using preErasureCtx)
-          (boundary eq defn.RootClass) ||
-          (ctx.owner.enclosingPackageClass eq boundary)
-        }
+        !cls.is(Flags.JavaDefined) ||
+          cls.isAccessibleFrom(cls.owner.thisType)(using preErasureCtx)
 
       @tailrec
       def recur(qual: Tree): Tree =

tests/pos/i24507-jframe.scala

@@ -0,0 +1,2 @@
+class Test extends javax.swing.JFrame { class Acc extends AccessibleJFrame }
+

tests/run/i24507.check

@@ -0,0 +1 @@
+foo

tests/run/i24507/A.java

@@ -0,0 +1,9 @@
+package a;
+
+public class A {
+  protected class B {
+    public String foo() {
+      return "foo";
+    }
+  }
+}

tests/run/i24507/test.scala

@@ -0,0 +1,12 @@
+// scalajs: --skip
+import a._
+
+class T extends A {
+  class Acc extends B
+  val acc = new Acc
+  def foo(): String = acc.foo()
+}
+
+@main def Test =
+  val t = new T
+  println(t.foo())