Simplify repainting logic in RenderLayer::recursiveUpdateLayerPositio…

…ns()

https://bugs.webkit.org/show_bug.cgi?id=264461
rdar://118151709

Reviewed by Alan Baradlay.

The `NeedsFullRepaint` case previously duplicate some logic that exists in `RenderElement::repaintAfterLayoutIfNeeded()`,
which is that if we're doing a full repaint, we just need to paint the clippedOverflowRects.

This logic was optimized in 270370@main to turn two repaints into one sometimes, and we can re-use it here. We know
that in the RequiresFullRepaint::Yes case, `RenderElement::repaintAfterLayoutIfNeeded()` only consults the clippedOverflowRects,
so we can fold this logic with the second `shouldRepaintAfterLayout()` clause. It's fine to pass empty oldRects if we didn't
have any.

`repaintAfterLayoutIfNeeded()` does the check for printing, so we can remove that. Also the comment duplicates comments
in that function too, so remove it.

* LayoutTests/fast/repaint/hidpi-box-with-subpixel-height-inflates-expected.txt:
* Source/WebCore/rendering/RenderLayer.cpp:
(WebCore::RenderLayer::recursiveUpdateLayerPositions):
(WebCore::RenderLayer::shouldRepaintAfterLayout const):

Canonical link: https://commits.webkit.org/270454@main

LayoutTests/fast/repaint/hidpi-box-with-subpixel-height-inflates-expected.txt

@@ -6,7 +6,6 @@ TEST COMPLETE
 (rect 0 48.50 22 1)
 (rect 0 49.50 800 152.50)
 (rect 0 49.50 800 152.50)
-(rect 1 1 1 47.50)
 (rect 1 1 1 200)
 )
 

Source/WebCore/rendering/RenderLayer.cpp

@@ -1037,27 +1037,14 @@ void RenderLayer::recursiveUpdateLayerPositions(RenderGeometryMap* geometryMap,
 
         auto oldRects = repaintRects();
         computeRepaintRects(repaintContainer.get(), geometryMap);
-
         auto newRects = repaintRects();
 
-        // FIXME: Should ASSERT that value calculated for m_outlineBox using the cached offset is the same
-        // as the value not using the cached offset, but we can't due to https://bugs.webkit.org/show_bug.cgi?id=37048
-        if ((flags & CheckForRepaint) && newRects) {
-            if (!renderer().view().printing()) {
-                if (m_repaintStatus == RepaintStatus::NeedsFullRepaint) {
-                    if (oldRects)
-                        renderer().repaintUsingContainer(repaintContainer.get(), oldRects->clippedOverflowRect);
-
-                    if (!oldRects || newRects->clippedOverflowRect != oldRects->clippedOverflowRect)
-                        renderer().repaintUsingContainer(repaintContainer.get(), newRects->clippedOverflowRect);
-
-                } else if (shouldRepaintAfterLayout()) {
-                    // FIXME: We will convert this to just take the old and new RepaintLayoutRects once
-                    // we change other callers to use RepaintLayoutRects.
-                    auto resolvedOldRects = valueOrDefault(oldRects);
-                    renderer().repaintAfterLayoutIfNeeded(repaintContainer.get(), RenderElement::RequiresFullRepaint::No, resolvedOldRects.clippedOverflowRect, resolvedOldRects.outlineBoundsRect,
-                        &newRects->clippedOverflowRect, &newRects->outlineBoundsRect);
-                }
+        if (flags.contains(CheckForRepaint) && newRects) {
+            ASSERT(isSelfPaintingLayer());
+            if (shouldRepaintAfterLayout()) {
+                auto needsFullRepaint = m_repaintStatus == RepaintStatus::NeedsFullRepaint ? RenderElement::RequiresFullRepaint::Yes : RenderElement::RequiresFullRepaint::No;
+                auto resolvedOldRects = valueOrDefault(oldRects);
+                renderer().repaintAfterLayoutIfNeeded(repaintContainer.get(), needsFullRepaint, resolvedOldRects.clippedOverflowRect, resolvedOldRects.outlineBoundsRect, &newRects->clippedOverflowRect, &newRects->outlineBoundsRect);
             }
         }
     } else
@@ -2047,7 +2034,7 @@ inline bool RenderLayer::shouldRepaintAfterLayout() const
         return false;
 #endif
 
-    if (m_repaintStatus == RepaintStatus::NeedsNormalRepaint)
+    if (m_repaintStatus == RepaintStatus::NeedsNormalRepaint || m_repaintStatus == RepaintStatus::NeedsFullRepaint)
         return true;
 
     // Composited layers that were moved during a positioned movement only