Ignore redundant calls to ScrollAnchor::save.

third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp

 // Copyright 2015 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 "core/layout/ScrollAnchor.h"
 
 #include "core/dom/ClientRect.h"
 #include "core/frame/VisualViewport.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutTestHelper.h"
@@ skipping 515 matching lines @@
         "    </div>"
         "</div>");
 
     Element* scroller = document().getElementById("scroller");
     scroller->setScrollTop(100);
 
     setHeight(document().getElementById("before"), 100);
     EXPECT_EQ(150, scrollerForElement(scroller)->scrollPosition().y());
 }
 
+TEST_F(ScrollAnchorTest, FlexboxDelayedAdjustmentRespectsSANACLAP)
+{
+    setBodyInnerHTML(
+        "<style>"
+        "    html { overflow: hidden; }"
+        "    body {"
+        "        position: absolute; display: flex;"
+        "        top: 0; bottom: 0; margin: 0;"
+        "    }"
+        "    #scroller { overflow: auto; }"
+        "    #spacer { width: 600px; height: 1200px; }"
+        "    #anchor {"
+        "        position: relative; top: 50px;"
+        "        width: 100px; height: 100px;"
+        "        background-color: #8f8;"
+        "    }"
+        "</style>"
+        "<div id='scroller'>"
+        "    <div id='spacer'>"
+        "        <div id='anchor'></div>"
+        "    </div>"
+        "</div>");
+
+    Element* scroller = document().getElementById("scroller");
+    scroller->setScrollTop(100);
+
+    document().getElementById("spacer")->setAttribute(
+        HTMLNames::styleAttr, "margin-top: 50px");
+    update();
+    EXPECT_EQ(100, scrollerForElement(scroller)->scrollPosition().y());
+}
+
 // Test then an element and its children are not selected as the anchor when
 // it has the overflow-anchor property set to none.
 TEST_F(ScrollAnchorTest, OptOutElement)
 {
     setBodyInnerHTML(
         "<style>"
         "     body { height: 1000px }"
         "     .div {"
         "          height: 100px; width: 100px;"
         "          border: 1px solid gray; background-color: #afa;"
@@ skipping 251 matching lines @@
         "    #a { width: 400px; height: 300px; }"
         "    .change { width: 100px; }"
         "</style>"
         "<div id='changer'></div>"
         "<div id='a'></div>");
 
     checkCorner(Corner::TopRight, DoublePoint(-20,  20), DoubleSize(-100, 0));
 }
 
 }