Bug 1405288 - Remove scrollIntoView actor method check from the inspector r=ochameau

The scrollIntoView actor method was added in bug 901250 3 years ago and
shipped with FF 40.
We support all the way back to the latest ESR (52 now).
So let's drop this backward compat check code.

MozReview-Commit-ID: 5FKRpiOXfzd

--HG--
extra : rebase_source : 4c3b0850750081a87b77bc1b85d7a2e852f58c82

devtools/client/inspector/inspector.js

@@ -131,7 +131,6 @@ function Inspector(toolbox) {
   this.onSidebarShown = this.onSidebarShown.bind(this);
 
   this._target.on("will-navigate", this._onBeforeNavigate);
-  this._detectingActorFeatures = this._detectActorFeatures();
 }
 
 Inspector.prototype = {
@@ -215,23 +214,6 @@ Inspector.prototype = {
     }
   },
 
-  /**
-   * Figure out what features the backend supports
-   */
-  _detectActorFeatures: function () {
-    this._supportsScrollIntoView = false;
-
-    // Use getActorDescription first so that all actorHasMethod calls use
-    // a cached response from the server.
-    return this._target.getActorDescription("domwalker").then(desc => {
-      return promise.all([
-        this._target.actorHasMethod("domnode", "scrollIntoView").then(value => {
-          this._supportsScrollIntoView = value;
-        }).catch(console.error)
-      ]);
-    });
-  },
-
   _deferredOpen: async function (defaultSelection) {
     this.breadcrumbs = new HTMLBreadcrumbs(this);
 
@@ -1374,7 +1356,6 @@ Inspector.prototype = {
       label: INSPECTOR_L10N.getStr("inspectorScrollNodeIntoView.label"),
       accesskey:
         INSPECTOR_L10N.getStr("inspectorScrollNodeIntoView.accesskey"),
-      hidden: !this._supportsScrollIntoView,
       disabled: !isSelectionElement,
       click: () => this.scrollNodeIntoView(),
     }));

devtools/client/inspector/markup/test/browser_markup_links_04.js

@@ -93,12 +93,6 @@ add_task(function* () {
     let linkFollow = allMenuItems.find(i => i.id === "node-menu-link-follow");
     let linkCopy = allMenuItems.find(i => i.id === "node-menu-link-copy");
 
-    // The contextual menu setup is async, because it needs to know if the
-    // inspector has the resolveRelativeURL method first. So call actorHasMethod
-    // here too to make sure the first call resolves first and the menu is
-    // properly setup.
-    yield inspector.target.actorHasMethod("inspector", "resolveRelativeURL");
-
     is(linkFollow.visible, test.isLinkFollowItemVisible,
       "The follow-link item display is correct");
     is(linkCopy.visible, test.isLinkCopyItemVisible,

devtools/client/inspector/test/shared-head.js

@@ -30,9 +30,6 @@ var openInspector = Task.async(function* (hostType) {
     yield inspector.once("inspector-updated");
   }
 
-  info("Waiting for actor features to be detected");
-  yield inspector._detectingActorFeatures;
-
   yield registerTestActor(toolbox.target.client);
   let testActor = yield getTestActor(toolbox);