Pressing tab closes Lastpass widget window

[srirambv]

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Yes

Describe the issue you encountered:
Pressing tab closes Lastpass widget window

Expected behavior:
Pressing tab should set focus to the next field

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Windows 10 x64

• Brave Version:
  0.12.1 RC1

• Steps to reproduce:

  1. Enable Lastpass as password manager from Preferences
  2. Click on the widget icon in URL bar
  3. Press tab, widget closes

• Screenshot if needed:
  Brave vs Chrome
  

• Any related issues:

  Setting milestone as 0.12.2 for now.