JVM IR: Use package visibility for $assertionsDisabled field

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/AssertionLowering.kt

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
 import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
+import org.jetbrains.kotlin.load.java.JavaVisibilities
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
@@ -140,6 +141,7 @@ fun IrClass.buildAssertionsDisabledField(backendContext: JvmBackendContext, topL
     buildField {
         name = Name.identifier(ASSERTIONS_DISABLED_FIELD_NAME)
         origin = JvmLoweredDeclarationOrigin.GENERATED_ASSERTION_ENABLED_FIELD
+        visibility = JavaVisibilities.PACKAGE_VISIBILITY
         type = backendContext.irBuiltIns.booleanType
         isFinal = true
         isStatic = true