set history #push and #pop

src/mechanize/history.cr

@@ -6,4 +6,19 @@ class MechanizeCr::History < Array(MechanizeCr::Page)
     @max_size = max_size
     super
   end
+
+  def push(page, uri = nil)
+    super page
+    while self.size > @max_size
+      shift
+    end
+    self
+  end
+
+  def pop
+    if size == 0
+      # TODO: raise error
+    end
+    page = super
+  end
 end