PLT-3181 Added crossorigin='anonymous' to all external images (#5774)

* PLT-3181 Added crossorigin='anonymous' to all external images

* Fixed image unit tests

* Added crossorigin='anonymous' to a few more places

webapp/tests/formatting_imgs.test.jsx

@@ -11,7 +11,7 @@ describe('Markdown.Imgs', function() {
     it('Inline mage', function(done) {
         assert.equal(
             Markdown.format('![Mattermost](/images/icon.png)').trim(),
-            '<p><img src="/images/icon.png" alt="Mattermost" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img"></p>'
+            '<p><img src="/images/icon.png" alt="Mattermost" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img" crossorigin="anonymous"></p>'
         );
 
         done();
@@ -20,7 +20,7 @@ describe('Markdown.Imgs', function() {
     it('Image with hover text', function(done) {
         assert.equal(
             Markdown.format('![Mattermost](/images/icon.png "Mattermost Icon")').trim(),
-            '<p><img src="/images/icon.png" alt="Mattermost" title="Mattermost Icon" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img"></p>'
+            '<p><img src="/images/icon.png" alt="Mattermost" title="Mattermost Icon" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img" crossorigin="anonymous"></p>'
         );
 
         done();
@@ -29,7 +29,7 @@ describe('Markdown.Imgs', function() {
     it('Image with link', function(done) {
         assert.equal(
             Markdown.format('[![Mattermost](../../images/icon-76x76.png)](https://github.com/mattermost/platform)').trim(),
-            '<p><a class="theme markdown__link" href="https://github.com/mattermost/platform" rel="noreferrer" target="_blank"><img src="../../images/icon-76x76.png" alt="Mattermost" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img"></a></p>'
+            '<p><a class="theme markdown__link" href="https://github.com/mattermost/platform" rel="noreferrer" target="_blank"><img src="../../images/icon-76x76.png" alt="Mattermost" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img" crossorigin="anonymous"></a></p>'
         );
 
         done();
@@ -38,7 +38,7 @@ describe('Markdown.Imgs', function() {
     it('Image with width and height', function(done) {
         assert.equal(
             Markdown.format('![Mattermost](../../images/icon-76x76.png =50x76 "Mattermost Icon")').trim(),
-            '<p><img src="../../images/icon-76x76.png" alt="Mattermost" title="Mattermost Icon" width="50" height="76" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img"></p>'
+            '<p><img src="../../images/icon-76x76.png" alt="Mattermost" title="Mattermost Icon" width="50" height="76" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img" crossorigin="anonymous"></p>'
         );
 
         done();
@@ -47,7 +47,7 @@ describe('Markdown.Imgs', function() {
     it('Image with width', function(done) {
         assert.equal(
             Markdown.format('![Mattermost](../../images/icon-76x76.png =50 "Mattermost Icon")').trim(),
-            '<p><img src="../../images/icon-76x76.png" alt="Mattermost" title="Mattermost Icon" width="50" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img"></p>'
+            '<p><img src="../../images/icon-76x76.png" alt="Mattermost" title="Mattermost Icon" width="50" onload="window.markdownImageLoaded(this)" onerror="window.markdownImageLoaded(this)" class="markdown-inline-img" crossorigin="anonymous"></p>'
         );
 
         done();