Allow absolute URLs in ShopifyApp::LoginProtection.redirection_javascript

[Hammadk]

The current ShopifyApp::LoginProtection.redirection_javascript only allows you to pass in a relative URL (/login). This is because we always set the location in #postMessage to:

data: { location: window.location.origin + #{url.to_json} }

Instead, we need to allow absolute URLs as well (https//SHOP.myshopify.com/admin/charges). We create a normalized link to do this:

normalizedLink = document.createElement('a');
normalizedLink.href = #{url.to_json};
data: { location: normalizedLink.href }

Tested in the following browsers:

• Canary Chrome 58
• Firefox 43.0.4
• Safari 10.0.3
• Chrome 56
• IE11 on Windows 7

Fixes #387

[gavinsmith]

makes sense to me 👍