Bug 1680218 - [devtools] Remove getAttributesInOwnerDocument trait. r=rcaliman.

The trait was introduced in Firefox 80, so it's
safe to remove it now.

Differential Revision: https://phabricator.services.mozilla.com/D98488

devtools/client/fronts/page-style.js

@@ -80,7 +80,7 @@ class PageStyleFront extends FrontClassWithSpec(pageStyleSpec) {
       throw new Error("`type` should not be empty");
     }
 
-    if (!this._form.traits.getAttributesInOwnerDocument || !search) {
+    if (!search) {
       return [];
     }
 

devtools/server/actors/page-style.js

@@ -178,8 +178,6 @@ var PageStyleActor = protocol.ActorClassWithSpec(pageStyleSpec, {
         // expected support of font-stretch at CSS Fonts Level 4.
         fontWeightLevel4:
           CSS.supports("font-weight: 1") && CSS.supports("font-stretch: 100%"),
-        // @backward-compat { version 80 }
-        getAttributesInOwnerDocument: true,
       },
     };
   },