Pasting into a input field causes a immediate crash

[luixxiul]

Describe the issue you encountered: Pasting into a input field causes a immediate crash

Expected behavior: It should not crash

• Platform (Win7, 8, 10? macOS? Linux distro?): Windows 10
• Brave Version: 0.12.2 RC1
• Steps to reproduce:
  1. Clear your brave folder temporarily and open the browser
  2. Go to https://github.com
  3. Paste https://github.com/brave/browser-laptop/issues/4164 into the field whose placeholder is "Pick a username"
  4. The browser crashes
• Screenshot if needed:
• Any related issues:

[luixxiul]

dup #4153 (and #4176)