Fix broken hash scroll logic (#4766)

`<Container>` does not receive any property. There is no way the *scrollToHash* logic can work right now. I believe it's a regression. It was working fine at some point. I'm sorry, I'm too lazy to add a test.

This fix was tested on Material-UI 👌.

This bug reproduction is the following:
As soon as you want to transition to a new page with a hash. The scroll doesn't change.
- start on pageA
- you scrollTop to 100
- you move to pageB#hash
- you stay at scrollTop 100, but #hash is at scrollTop 400.

lib/app.js

@@ -61,7 +61,7 @@ export class Container extends Component {
   }
 
   scrollToHash () {
-    const { hash } = this.props
+    const { hash } = this.context._containerProps
     if (!hash) return
 
     const el = document.getElementById(hash)
@@ -73,8 +73,7 @@ export class Container extends Component {
   }
 
   render () {
-    const {children} = this.props
-    return <>{children}</>
+    return this.props.children
   }
 }
 

test/integration/basic/pages/nav/index.js

@@ -53,6 +53,7 @@ export default class extends Component {
           Counter: {counter}
         </div>
         <button id='increase' onClick={() => this.increase()}>Increase</button>
+        <Link href='/nav/hash-changes#item-400'><a id='scroll-to-hash'>Scroll to hash</a></Link>
       </div>
     )
   }

test/integration/basic/test/client-navigation.js

@@ -248,7 +248,7 @@ export default (context, render) => {
           browser.close()
         })
 
-        it('should scroll to the specified position', async () => {
+        it('should scroll to the specified position on the same page', async () => {
           let browser
           try {
             browser = await webdriver(context.appPort, '/nav/hash-changes')
@@ -272,6 +272,25 @@ export default (context, render) => {
             }
           }
         })
+
+        it('should scroll to the specified position to a new page', async () => {
+          let browser
+          try {
+            browser = await webdriver(context.appPort, '/nav')
+
+            // Scrolls to item 400 on the page
+            await browser
+              .elementByCss('#scroll-to-hash').click()
+              .waitForElementByCss('#hash-changes-page')
+
+            const scrollPosition = await browser.eval('window.pageYOffset')
+            expect(scrollPosition).toBe(7258)
+          } finally {
+            if (browser) {
+              browser.close()
+            }
+          }
+        })
       })
 
       describe('when hash change via A tag', () => {