Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/reflection/enclosing/lambdaInPropertyGetter.kt

@@ -0,0 +1,18 @@
+// WITH_REFLECT
+
+val l: Any
+    get() = {}
+
+fun box(): String {
+
+    val enclosingMethod = l.javaClass.getEnclosingMethod()
+    if (enclosingMethod?.getName() != "getL") return "method: $enclosingMethod"
+
+    val enclosingClass = l.javaClass.getEnclosingClass()!!.getName()
+    if (enclosingClass != "LambdaInPropertyGetterKt") return "enclosing class: $enclosingClass"
+
+    val declaringClass = l.javaClass.getDeclaringClass()
+    if (declaringClass != null) return "anonymous function has a declaring class: $declaringClass"
+
+    return "OK"
+}