Fixed scroll position maintenance

[devbucket]

Description

When navigating from a scrolled category page to the product page and back, you wouldn't be brought back to the scrolled position you left the page. This has been fixed.

Type of change

Please add an "x" into the option that is relevant:

• [ x ] Bug Fix 🐛 (non-breaking change which fixes an issue)
• [ ] New Feature 🚀 (non-breaking change which adds functionality)
• [ ] Breaking Change 💥 (fix or feature that would cause existing functionality to not work as expected)
• [ ] Polish 💅 (Just some cleanups)
• [ ] Docs 📝 (Changes in the documentations)
• [ ] Internal 🏠 Only relates to internal processes.

How to test it

Navigate to a category page with many products, scroll for a bit and click on a product. Then navigate back. You should be at the same position, you have left before.

[coveralls]

Pull Request Test Coverage Report for Build 1916

• 8 of 14 (57.14%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 46.879%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/common/reducers/router/index.js	0	1	0.0%
libraries/common/selectors/router.js	4	5	80.0%
themes/theme-gmd/pages/Category/subscriptions.js	0	2	0.0%
themes/theme-ios11/pages/Category/subscriptions.js	0	2	0.0%

Totals
Change from base Build 1914:	0.04%
Covered Lines:	4955
Relevant Lines:	9905

---

💛 - Coveralls