Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/reflection/genericSignature/kt6106.kt

@@ -0,0 +1,28 @@
+// WITH_REFLECT
+
+package test
+
+open class B
+
+class A {
+
+    companion object {
+        @JvmStatic
+        fun <T: B> a(s: T) : T {
+            return s
+        }
+    }
+}
+
+fun box(): String {
+    val method = A::class.java.getDeclaredMethod("a", B::class.java)
+    val genericParameterTypes = method.getGenericParameterTypes()
+
+    if (genericParameterTypes.size != 1) return "Wrong number of generic parameters"
+
+    if (genericParameterTypes[0].toString() != "T") return "Wrong parameter type ${genericParameterTypes[0].toString()}"
+
+    if (method.getGenericReturnType().toString() != "T") return "Wrong return type ${method.getGenericReturnType()}"
+
+    return "OK"
+}