Remove duplicate fonts

[fmarier]

Fixes brave/brave-browser#6832 and brave/brave-browser#6881.

Submitter Checklist:

• 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).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

I added some borders in the existing files:

diff --git a/components/fonts/muli.css b/components/fonts/muli.css
index 4652c3a75..9b3b4254d 100644
--- a/components/fonts/muli.css
+++ b/components/fonts/muli.css
@@ -1,3 +1,4 @@
+* { border: 10px solid red !important }
 /* vietnamese */
 @font-face {
     font-family: 'Muli';
diff --git a/ui/webui/resources/fonts/muli.css b/ui/webui/resources/fonts/muli.css
index 578a1ec66..53ec5c8f6 100644
--- a/ui/webui/resources/fonts/muli.css
+++ b/ui/webui/resources/fonts/muli.css
@@ -1,3 +1,4 @@
+* { border: 10px solid blue !important }
 /* vietnamese */
 @font-face {
     font-family: 'Muli';

so that I could see red borders on:

• newtab page
• http://releases.ubuntu.com/19.10/ubuntu-19.10-desktop-amd64.iso.torrent
• brave://rewards
• Rewards main extension panel
• Rewards tip panel
• brave://welcome
• brave://sync
• Shields main extension panel

and blue ones on:

• brave://settings
• brave://history

After my change, everything looked blue, as expected. I then applied a similar patch for the other font:

diff --git a/components/fonts/poppins.css b/components/fonts/poppins.css
index 82c9931d1..97b27af07 100644
--- a/components/fonts/poppins.css
+++ b/components/fonts/poppins.css
@@ -1,4 +1,4 @@
-
+* { border: 10px solid green !important }
 /* devanagari */
 @font-face {
     font-family: 'Poppins';
diff --git a/ui/webui/resources/fonts/poppins.css b/ui/webui/resources/fonts/poppins.css
index 6221834f6..8519fd548 100644
--- a/ui/webui/resources/fonts/poppins.css
+++ b/ui/webui/resources/fonts/poppins.css
@@ -1,3 +1,4 @@
+* { border: 10px solid yellow !important }
 /* devanagari */
 @font-face {
     font-family: 'Poppins';

and looked for green borders instead of red, and yellow borders instead of blue.

After my patch, everything went yellow as expected, except for WebTorrent which doesn't use Poppins for some reason.

Finally, I also verified that I hadn't broken the following:

• chrome://brave-resources/fonts/muli.css
• chrome://brave-resources/fonts/poppins.css

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[NejcZdovc]

rewards changes looks good

[petemill]

This looks good but I'd like to test out some rendering and webpack bundling, which I won't be able to get to until Wednesday. If it's more pressing than that, go ahead and merge following others' approval and I'll create follow up issues if I find anything.

[emerick]

LGTM

[fmarier]

This looks good but I'd like to test out some rendering and webpack bundling, which I won't be able to get to until Wednesday. If it's more pressing than that, go ahead and merge following others' approval and I'll create follow up issues if I find anything.

@petemill It can wait until Wednesday, no problems.

[petemill]

Checked the rendering, all looks good. Looks like the affected pages weren't optimized to begin with 🤦‍♂, so we're ok.
Thanks for fixing the duplication 🏅