Bug 1644230 - Set color inheritance on newtab icons r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D78980

browser/components/newtab/content-src/components/Base/_Base.scss

@@ -118,8 +118,8 @@ main {
   button {
     background-color: transparent;
     border: 0;
+    border-radius: 2px;
     cursor: pointer;
-    fill: var(--newtab-icon-primary-color);
     inset-inline-end: 15px;
     padding: 15px;
     position: fixed;

browser/components/newtab/content-src/styles/_icons.scss

@@ -4,7 +4,8 @@
   background-size: $icon-size;
   -moz-context-properties: fill;
   display: inline-block;
-  fill: var(--newtab-icon-primary-color);
+  color: var(--newtab-icon-primary-color);
+  fill: currentColor;
   height: $icon-size;
   vertical-align: middle;
   width: $icon-size;

browser/components/newtab/css/activity-stream-linux.css

@@ -142,7 +142,8 @@ body {
   background-size: 16px;
   -moz-context-properties: fill;
   display: inline-block;
-  fill: var(--newtab-icon-primary-color);
+  color: var(--newtab-icon-primary-color);
+  fill: currentColor;
   height: 16px;
   vertical-align: middle;
   width: 16px; }
@@ -440,8 +441,8 @@ main {
 .prefs-button button {
   background-color: transparent;
   border: 0;
+  border-radius: 2px;
   cursor: pointer;
-  fill: var(--newtab-icon-primary-color);
   inset-inline-end: 15px;
   padding: 15px;
   position: fixed;

browser/components/newtab/css/activity-stream-mac.css

@@ -145,7 +145,8 @@ body {
   background-size: 16px;
   -moz-context-properties: fill;
   display: inline-block;
-  fill: var(--newtab-icon-primary-color);
+  color: var(--newtab-icon-primary-color);
+  fill: currentColor;
   height: 16px;
   vertical-align: middle;
   width: 16px; }
@@ -443,8 +444,8 @@ main {
 .prefs-button button {
   background-color: transparent;
   border: 0;
+  border-radius: 2px;
   cursor: pointer;
-  fill: var(--newtab-icon-primary-color);
   inset-inline-end: 15px;
   padding: 15px;
   position: fixed;

browser/components/newtab/css/activity-stream-windows.css

@@ -142,7 +142,8 @@ body {
   background-size: 16px;
   -moz-context-properties: fill;
   display: inline-block;
-  fill: var(--newtab-icon-primary-color);
+  color: var(--newtab-icon-primary-color);
+  fill: currentColor;
   height: 16px;
   vertical-align: middle;
   width: 16px; }
@@ -440,8 +441,8 @@ main {
 .prefs-button button {
   background-color: transparent;
   border: 0;
+  border-radius: 2px;
   cursor: pointer;
-  fill: var(--newtab-icon-primary-color);
   inset-inline-end: 15px;
   padding: 15px;
   position: fixed;