Favicons need onerror handler (as seen in about:newtab)

[bsclifton]

Did you search for similar issues before submitting this one?
Yes

Describe the issue you encountered:
Favicons are loaded throughout the browser. When they are missing, it looks really bad, since there is not a fallback image.

Expected behavior:
For about:newtab, the tiles can fallback to the letter being used. For other places, a default document icon can be used.

NOTE: this is a great opportunity to create a new React control which loads the image using background-url... but also loads the image using a hidden tag, which has the onerror handler. This functionality can be used in multiple places, including the background image that's shown in about:newtab

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

• Brave Version:
  0.12.9 and newer

• Steps to reproduce:

  1. Go to a site that has a broken favicon
  2. Go to about:newtab
  3. Notice favicon is broken

• Screenshot if needed:
  one to look for is in the top left tile
  

• Any related issues:

[luixxiul]

This should be fixed soon.

[luixxiul]

Test plan: #5826 (comment)