Test referring to lowercase class name inside class.

Fix #251.

test/language/class/lowercase_name_inside_body.wren

@@ -0,0 +1,15 @@
+class foo {
+  static callFoo {
+    IO.print(foo)
+  }
+
+  callFoo {
+    IO.print(foo)
+  }
+
+  foo { "instance foo method" }
+  static foo { "static foo method" }
+}
+
+foo.callFoo // expect: static foo method
+(new foo).callFoo // expect: instance foo method