Cleanup CompositingReasonFinder::requiresCompositingForPosition

Source/web/ChromeClientImpl.cpp

Index: Source/web/ChromeClientImpl.cpp
diff --git a/Source/web/ChromeClientImpl.cpp b/Source/web/ChromeClientImpl.cpp
index 17d9d3268ed1f550e52259af7182df177b6d1ca5..0a42eb721f32be3bf34afae4e99897917cfe2a0d 100644
--- a/Source/web/ChromeClientImpl.cpp
+++ b/Source/web/ChromeClientImpl.cpp
@@ -745,6 +745,10 @@ WebCore::CompositingTriggerFlags ChromeClientImpl::allowedCompositingTriggers()
         flags |= WebCore::LegacyOverflowScrollTrigger;
     if (settings.compositorDrivenAcceleratedScrollingEnabled())
         flags |= WebCore::OverflowScrollTrigger;
+    // FIXME: acceleratedCompositingForFixedPositionEnabled should be renamed acceleratedCompositingForViewportConstrainedPositionEnabled().
+    // Or the sticky and fixed position elements should be behind different flags.
+    if (settings.acceleratedCompositingForFixedPositionEnabled())
+        flags |= WebCore::ViewportConstrainedPositionedTrigger;
 
     return flags;
 }