Bug 1469959 - Don't use relatedTarget to check if the ObjectInspector was focused by tabbing; r=bgrins.

Basically this rolls back the changes made to the reps bundle
in Bug 1463415. This change will be backported in Github later
so the fix can ride the train.
A test is added to make sure we don't regress again.

MozReview-Commit-ID: Csak2pPyTOR

--HG--
extra : rebase_source : a3f24dab9e062f0743cdbc4e9cec9d1ce62c86d1

devtools/client/shared/components/reps/reps.js

@@ -4445,12 +4445,12 @@ class Tree extends Component {
           return;
         }
 
-        const { relatedTarget } = nativeEvent;
+        const { explicitOriginalTarget } = nativeEvent;
 
         // Only set default focus to the first tree node if the focus came
         // from outside the tree (e.g. by tabbing to the tree from other
         // external elements).
-        if (relatedTarget !== this.treeRef && !this.treeRef.contains(relatedTarget)) {
+        if (explicitOriginalTarget !== this.treeRef && !this.treeRef.contains(explicitOriginalTarget)) {
           this._focus(traversal[0].item);
         }
       },

devtools/client/webconsole/test/mochitest/browser.ini

@@ -321,6 +321,7 @@ skip-if = (os == 'linux') || (os == 'win' && os_version == '10.0' && debug && bi
 [browser_webconsole_object_inspector_key_sorting.js]
 [browser_webconsole_object_inspector_local_session_storage.js]
 [browser_webconsole_object_inspector_selected_text.js]
+[browser_webconsole_object_inspector_scroll.js]
 [browser_webconsole_object_inspector_while_debugging_and_inspecting.js]
 [browser_webconsole_observer_notifications.js]
 [browser_webconsole_optimized_out_vars.js]

devtools/client/webconsole/test/mochitest/browser_webconsole_object_inspector_scroll.js

@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Check that expanding an objectInspector node doesn't alter the output scroll position.
+const TEST_URI = "data:text/html;charset=utf8,test Object Inspector";
+
+add_task(async function() {
+  const hud = await openNewTabAndConsole(TEST_URI);
+
+  await ContentTask.spawn(gBrowser.selectedBrowser, null, function() {
+    content.wrappedJSObject.console.log("oi-test", content.wrappedJSObject.Math);
+  });
+
+  const node = await waitFor(() => findMessage(hud, "oi-test"));
+  const objectInspector = node.querySelector(".tree");
+
+  let onOiMutation = waitForNodeMutation(objectInspector, {
+    childList: true
+  });
+
+  info("Expanding the object inspector");
+  objectInspector.querySelector(".arrow").click();
+  await onOiMutation;
+
+  const nodes = objectInspector.querySelectorAll(".node");
+  const lastNode = nodes[nodes.length - 1];
+
+  info("Scroll the last node of the ObjectInspector into view");
+  lastNode.scrollIntoView();
+
+  const outputContainer = hud.ui.outputNode.querySelector(".webconsole-output");
+  ok(hasVerticalOverflow(outputContainer), "There is a vertical overflow");
+  const scrollTop = outputContainer.scrollTop;
+
+  onOiMutation = waitForNodeMutation(objectInspector, {
+    childList: true
+  });
+
+  info("Expand the last node");
+  const view = lastNode.ownerDocument.defaultView;
+  EventUtils.synthesizeMouseAtCenter(lastNode, {}, view);
+
+  await onOiMutation;
+
+  is(scrollTop, outputContainer.scrollTop,
+    "Scroll position did not changed when expanding a node");
+});
+
+function hasVerticalOverflow(container) {
+  return container.scrollHeight > container.clientHeight;
+}