Unable to KYC on uphold when Shields are up

[btlechowski]

Can't click Start session. Got an Page unresponsive error

Steps to Reproduce

1. Create an account on https://sandbox.uphold.com/
2. Try to verify using your webcam

Note: This issue does not reproduce on Brave on Android
Note: Not reproducible when Shields are down

Actual result:

Can't click Start session
Got an Page unresponsive error

Expected result:

Able to verify

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave	1.14.84 Chromium: 85.0.4183.121 (Official Build) (64-bit)
Revision	a81aa729a8e1fd413943a339393c82e7b8055ddc-refs/branch-heads/4183@{#1864}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

Brave	1.15.63 Chromium: 86.0.4240.55 (Official Build) dev (64-bit)
Revision	a6d625ef6f7fe8ea0675f1cf759155a05ee1be40-refs/branch-heads/4240@{#953}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

Brave	1.16.39 Chromium: 86.0.4240.55 (Official Build) nightly (64-bit)
Revision	a6d625ef6f7fe8ea0675f1cf759155a05ee1be40-refs/branch-heads/4240@{#953}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

cc @brave/legacy_qa @rebron @NejcZdovc @jsecretan