Updating icons in URL bar

[bsclifton]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Updating icons in URL bar

Fixes #5446
Fixes #4910

• includes updates to the webdriver tests (and adding new test case for this)
• colors for icon in URL bar pulled out into variables.less

Auditors: @diracdeltas, @bbondy

Test Plan

1. Launch Brave and open a new tab
2. Notice that magnifying glass shows by default (with no text input yet)
3. Type some text and notice icon remains magnifying glass (no longer the document icon)
4. Visit http://mal-game.com
5. Notice the triangle exclamation icon is now showing, since connection is HTTP
6. Click the triangle in the URL bar and confirm you see the "insecure connection" modal
7. Visit https://mixed-script.badssl.com/
8. Click the lock icon in the URL bar
9. Secure connection modal comes up. Click "Load Unsafe Scripts"
10. Notice icon in URL bar is now the triangle
11. Click the triangle icon in the URL bar and confirm you see the "partially insecure connection" modal

Screenshots

HTTP shows yellow triangle now

Insecure/partially insecure modal uses triangle

URL bar (when empty) now defaults to magnifying glass

when typing into URL bar, it shows magnifying glass instead of document

[bbondy]

excellent, thanks!