Auto merge of #7064 - paulrouget:reload, r=Ms2ger

Implement location.reload()

This is a naive implementation of `window.location.reload()`.
I'd appreciate any feedback.

I was wondering if it'd be better to implement `ConstellationMsg::Reload` instead of using  `load_url`.

Also, what kind of test should I write?

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components/script/dom/webidls/Location.webidl

@@ -7,6 +7,6 @@
 /*[Unforgeable]*/ interface Location {
   void assign(DOMString url);
   //void replace(DOMString url);
-  //void reload();
+  void reload();
 };
 Location implements URLUtils;