Bug 1929594 - [devtools] Use --theme-text-color-inactive for disabled menu items instead of tweaking the opacity. r=devtools-reviewers,ochameau.

This makes the element nicely adapt to High Contrast Mode.

Differential Revision: https://phabricator.services.mozilla.com/D228191

devtools/client/themes/tooltips.css

@@ -579,7 +579,7 @@ strong {
     }
 
     &[disabled] {
-      opacity: 0.5;
+      color: var(--theme-text-color-inactive);
     }
 
     &[aria-checked="true"] {
@@ -613,10 +613,13 @@ strong {
   .menuitem > button.command:is([role="menuitem"],[role="menuitemcheckbox"],[role="link"]) {
     appearance: none;
     border: none;
-    color: var(--theme-arrowpanel-color);
     background-color: transparent;
     text-align: start;
     width: 100%;
+
+    &:not([disabled]) {
+      color: var(--theme-arrowpanel-color);
+    }
   }
 
   .checkbox-container .menuitem > .command > .label {