Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/jvmName/multifileClassWithLocalClass.kt

@@ -0,0 +1,13 @@
+// WITH_RUNTIME
+
+@file:JvmName("Test")
+@file:JvmMultifileClass
+package test
+
+fun foo(): String = bar()
+fun bar(): String {
+    class Local(val x: String)
+    return Local("OK").x
+}
+
+fun box(): String = foo()