Build fix after 160450@main by guarding showRenderTree

https://bugs.webkit.org/show_bug.cgi?id=260702

Unreviewed build fix.

Where LOG_DISABLED is disabled, the build fails due to missing showRenderTree().
The showRenderTree() is guarded by ENABLE(TREE_DEBUGGING).

* Source/WebCore/page/LocalFrameViewLayoutContext.cpp:
(WebCore::LocalFrameViewLayoutContext::performLayout):

Canonical link: https://commits.webkit.org/267268@main

Source/WebCore/page/LocalFrameViewLayoutContext.cpp

@@ -240,7 +240,7 @@ void LocalFrameViewLayoutContext::performLayout()
 #endif
         clearSubtreeLayoutRoot();
 
-#if !LOG_DISABLED
+#if !LOG_DISABLED && ENABLE(TREE_DEBUGGING)
         auto layoutLogEnabled = [] {
             return LogLayout.state == WTFLogChannelState::On;
         };