Avoid layout/full-repaint on view height change if possible

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 8e541dbcf7876b8c1adc4bd5a113fcf1ad8646a8..e1a5d35000c76b03428c803414fd9e3a824f9d4a 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -3492,7 +3492,17 @@ void FrameView::setLayoutSizeInternal(const IntSize& size)
         return;
 
     m_layoutSize = size;
-    contentsResized();
+
+    // Update scrollbars. Not calling this->contentsResized() to avoid setNeedsLayout.
+    ScrollView::contentsResized();
+
+    if (RenderView* renderView = this->renderView()) {
+        renderView->viewResized();
+        // If selfNeedsLayout, resize event will be sent if needed during the next layout;
+        // otherwise we need to send the resize event now if needed.
+        if (!renderView->selfNeedsLayout())
+            sendResizeEventIfNeeded();
+    }
 }
 
 void FrameView::didAddScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)