Web Inspector: Computed Panel: Assertion Failed: Cannot remove view w…

…hich isn't a subview. ComputedStyleSection

https://bugs.webkit.org/show_bug.cgi?id=240644

Reviewed by Patrick Angle.

The root cause for this failed assertion is an accumulation of orphaned `WI.ComputedStyleSection` view instances in
`WI.ComputedStyleDetailsPanel._detailsSectionByStyleSectionMap`.

When `WI.ComputedStyleDetailsPanel.layout()` is called to reflect the latest selected node's variables, the previous `WI.ComputedStyleSection` view instance for ungrouped
variables is accidentally kept around. When attempting to remove this view on the next `layout()` run, this orphaned instance has no
host node that belongs to the parent view so the assertion fails. The issue gets progressively worse on each `layout()` run by accumulating more orphans.

* Source/WebInspectorUI/UserInterface/Views/ComputedStyleDetailsPanel.js: (WI.ComputedStyleDetailsPanel.prototype.layout):

Canonical link: https://commits.webkit.org/250763@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@294506 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebInspectorUI/UserInterface/Views/ComputedStyleDetailsPanel.js

@@ -215,13 +215,11 @@ WI.ComputedStyleDetailsPanel = class ComputedStyleDetailsPanel extends WI.StyleD
             this.element.appendChild(styleSection.element);
             this.removeSubview(styleSection);
             styleSection.element.remove();
+            this._detailsSectionByStyleSectionMap.delete(styleSection);
 
             // The top-level details section for variables needs to be preserved because it's the host of nested details sections for variables groups.
-            if (detailsSection === this._variablesSection)
-                continue;
-
-            detailsSection.element.remove();
-            this._detailsSectionByStyleSectionMap.delete(styleSection);
+            if (detailsSection !== this._variablesSection)
+                detailsSection.element.remove();
         }
 
         this._variablesStyleSectionForGroupTypeMap.clear();