Steps to reproduce:
1. Open attached project
2. "New Unity Project.zip"
3. Build and run on android
4. On the device press "Show" to show the web view, and Load url to load Google.
5. Scroll down to the input field and press it to make the keyboard appear
6. Web view disappears

Expected: The webview should be visible, that's where I'm inputting things, so I should see where I'm typing
Actual: The view is gone, sometimes possible to reappear it by toggling some window features, but generally it's not visible

Reproduced on: 2018.1.0a6, 2017.3.0b11, 2017.2.0p3, 2017.1.2p3

Devices Under Test:
Amazon KFFOWI (Fire (2015)), OS:5.1.1, CPU:armeabi-v7a, GPU:Mali-450 MP, Build:Amazon/full_ford/ford:5.1.1/LVY48F/37.5.9.5_user_595457220:user/release-keys

Htc HTC 10, OS:7.0, CPU:arm64-v8a, GPU:Adreno (TM) 530, Build:htc/pmeuhl_00401/htc_pmeuhl:7.0/NRD90M/857212.41:user/release-keys

Samsung SM G800F (Galaxy S5 Mini)*, OS:6.0.1, CPU:armeabi-v7a, GPU:Mali-400 MP, Build:samsung/kminiltexx/kminilte:6.0.1/MMB29K/G800FXXU1CQA1:user/release-keys