Don't restore in LayoutBlock::layout if clamping is delayed.

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

Index: third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp
diff --git a/third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp b/third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp
index fe3148aac88e7df7fe9d197eb0dd207cb89f19ed..9035f2f6c664cf0abdae702a48052769609cef39 100644
--- a/third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp
+++ b/third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp
@@ -561,6 +561,37 @@ TEST_F(ScrollAnchorTest, DescendsIntoContainerWithFloat)
         scrollAnchor(viewport).anchorObject());
 }
 
+TEST_F(ScrollAnchorTest, FlexboxDelayedClampingAlsoDelaysAdjustment)
+{
+    setBodyInnerHTML(
+        "<style>"
+        "    html { overflow: hidden; }"
+        "    body {"
+        "        position: absolute; display: flex;"
+        "        top: 0; bottom: 0; margin: 0;"
+        "    }"
+        "    #scroller { overflow: auto; }"
+        "    #spacer { width: 600px; height: 1200px; }"
+        "    #before { height: 50px; }"
+        "    #anchor {"
+        "        width: 100px; height: 100px;"
+        "        background-color: #8f8;"
+        "    }"
+        "</style>"
+        "<div id='scroller'>"
+        "    <div id='spacer'>"
+        "        <div id='before'></div>"
+        "        <div id='anchor'></div>"
+        "    </div>"
+        "</div>");
+
+    Element* scroller = document().getElementById("scroller");
+    scroller->setScrollTop(100);
+
+    setHeight(document().getElementById("before"), 100);
+    EXPECT_EQ(150, 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)