Remove ScrollableArea::notifyScrollPositionChanged and cleanup scroll animators.

Source/core/frame/RootFrameViewportTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/frame/RootFrameViewport.h"
 
 #include "core/layout/ScrollAlignment.h"
 #include "platform/geometry/DoubleRect.h"
@@ skipping 367 matching lines @@
         ScrollAlignment::alignToEdgeIfNeeded,
         ScrollAlignment::alignToEdgeIfNeeded);
     EXPECT_POINT_EQ(DoublePoint(100, 150), layoutViewport.scrollPositionDouble());
     EXPECT_POINT_EQ(DoublePoint(50, 75), visualViewport.scrollPositionDouble());
 
     // Scrolling into view the viewport rect itself should be a no-op.
     visualViewport.setViewportSize(IntSize(100, 100));
     visualViewport.setScale(1.5f);
     visualViewport.setScrollPosition(DoublePoint(0, 10), ProgrammaticScroll);
     layoutViewport.setScrollPosition(DoublePoint(50, 50), ProgrammaticScroll);
-    rootFrameViewport->notifyScrollPositionChanged(rootFrameViewport->scrollPositionDouble());
+    rootFrameViewport->setScrollPosition(rootFrameViewport->scrollPositionDouble(), ProgrammaticScroll);
 
     rootFrameViewport->scrollIntoView(
         LayoutRect(rootFrameViewport->visibleContentRectDouble(ExcludeScrollbars)),
         ScrollAlignment::alignToEdgeIfNeeded,
         ScrollAlignment::alignToEdgeIfNeeded);
     EXPECT_POINT_EQ(DoublePoint(50, 50), layoutViewport.scrollPositionDouble());
     EXPECT_POINT_EQ(DoublePoint(0, 10), visualViewport.scrollPositionDouble());
 
     rootFrameViewport->scrollIntoView(
         LayoutRect(rootFrameViewport->visibleContentRectDouble(ExcludeScrollbars)),
@@ skipping 94 matching lines @@
     ScrollResult result = rootFrameViewport->handleWheel(wheelEvent);
 
     EXPECT_TRUE(result.didScroll());
     EXPECT_POINT_EQ(DoublePoint(50, 50), visualViewport.scrollPositionDouble());
     EXPECT_POINT_EQ(DoublePoint(100, 200), layoutViewport.scrollPositionDouble());
     EXPECT_EQ(-350, result.unusedScrollDeltaX);
     EXPECT_EQ(-250, result.unusedScrollDeltaY);
 }
 
 } // namespace blink