bug: pull to refresh ios - content transforms which leaves blank space when scrolling

# Bug Report

**Ionic version:**
[x] **4.x**

**Current behavior:**
Pull to refresh. When performing this in chrome/safari/android content receives `overflow: hidden`.
But on iOS device it's possible to scroll content during refresh action. And then it looks very strange: Spinner disappears and just background left over the screen.

**Expected behavior:**
I think in every device content should get `overflow: hidden`

**Related code:**

Looks like the problem in next method in line 656:

https://github.com/ionic-team/ionic/blob/3937101e5c2b181a6b7926eb8386c22b0f887716/core/src/components/refresher/refresher.tsx#L655-L669

But I don't understand what does it mean here, this nativeRefresher and why in this case `overflow: hidden` shouldn't be set on ion-content