Clamping shouldn't clear the fragment anchor.

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 3617 matching lines @@
   if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
     // Don't scroll the FrameView!
     ASSERT_NOT_REACHED();
   }
 
   m_scrollOffset = offset;
 
   if (!scrollbarsSuppressed())
     m_pendingScrollDelta += scrollDelta;
 
-  clearFragmentAnchor();
+  if (scrollTypeClearsFragmentAnchor(scrollType))
+    clearFragmentAnchor();
   updateLayersAndCompositingAfterScrollIfNeeded(scrollDelta);
 
   Document* document = m_frame->document();
   document->enqueueScrollEventForNode(document);
 
   m_frame->eventHandler().dispatchFakeMouseMoveEventSoon();
   Page* page = frame().page();
   if (page)
     page->chromeClient().clearToolTip(*m_frame);
 
@@ skipping 861 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink