Only create sticky position constraints for constrained sticky position.

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

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp b/third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp
index 2075455464a254e8ad6aab65699330b30d5f2476..0001d9c90b14bcf3cadb4d33c634c714cf74f57e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObjectTest.cpp
@@ -339,11 +339,18 @@ TEST_F(LayoutBoxModelObjectTest, StickyPositionConstraintInvalidation) {
 TEST_F(LayoutBoxModelObjectTest,
        StickyPositionFindsCorrectStickyBoxShiftingAncestor) {
   setBodyInnerHTML(
-      "<style>#stickyOuterDiv { position: sticky; }"
-      "#stickyOuterInline { position: sticky; display: inline; }"
-      "#stickyInnerInline { position: sticky; display: inline; }</style>"
-      "<div id='stickyOuterDiv'><div id='stickyOuterInline'>"
-      "<div id='stickyInnerInline'></div></div></div>");
+      "<style>#stickyOuterDiv { position: sticky; top: 0;}"
+      "#stickyOuterInline { position: sticky; top: 0; display: inline; }"
+      "#unanchoredSticky { position: sticky; display: inline; }"
+      "#stickyInnerInline { position: sticky; top: 0; display: inline; "
+      "}</style>"
+      "<div id='stickyOuterDiv'>"
+      "  <div id='stickyOuterInline'>"
+      "    <div id='unanchoredSticky'>"
+      "      <div id='stickyInnerInline'></div>"
+      "    </div>"
+      "  </div>"
+      "</div>");
 
   LayoutBoxModelObject* stickyOuterDiv =
       toLayoutBoxModelObject(getLayoutObjectByElementId("stickyOuterDiv"));
@@ -386,12 +393,19 @@ TEST_F(LayoutBoxModelObjectTest,
   // We make the scroller itself sticky in order to check that elements do not
   // detect it as their containing-block shifting ancestor.
   setBodyInnerHTML(
-      "<style>#scroller { overflow-y: scroll; position: sticky; }"
-      "#stickyParent { position: sticky; }"
-      "#stickyChild { position: sticky; }"
-      "#stickyNestedChild { position: sticky; }</style>"
-      "<div id='scroller'><div id='stickyParent'><div id='stickyChild'></div>"
-      "<div><div id='stickyNestedChild'></div></div></div></div>");
+      "<style>#scroller { overflow-y: scroll; position: sticky; top: 0;}"
+      "#stickyParent { position: sticky; top: 0;}"
+      "#stickyChild { position: sticky; top: 0;}"
+      "#unanchoredSticky { position: sticky; }"
+      "#stickyNestedChild { position: sticky; top: 0;}</style>"
+      "<div id='scroller'>"
+      "  <div id='stickyParent'>"
+      "    <div id='unanchoredSticky'>"
+      "      <div id='stickyChild'></div>"
+      "      <div><div id='stickyNestedChild'></div></div>"
+      "    </div>"
+      "  </div>"
+      "</div>");
 
   LayoutBoxModelObject* scroller =
       toLayoutBoxModelObject(getLayoutObjectByElementId("scroller"));
@@ -418,7 +432,8 @@ TEST_F(LayoutBoxModelObjectTest,
                    .nearestStickyBoxShiftingContainingBlock());
 
   // Both inner children should detect the parent <div> as their
-  // containing-block shifting ancestor.
+  // containing-block shifting ancestor. They skip past unanchored sticky
+  // because it will never have a non-zero offset.
   EXPECT_EQ(stickyParent,
             constraintsMap.at(stickyChild->layer())
                 .nearestStickyBoxShiftingContainingBlock());
@@ -435,8 +450,8 @@ TEST_F(LayoutBoxModelObjectTest,
 TEST_F(LayoutBoxModelObjectTest,
        StickyPositionFindsCorrectContainingBlockShiftingAncestorRoot) {
   setBodyInnerHTML(
-      "<style>#stickyParent { position: sticky; }"
-      "#stickyGrandchild { position: sticky; }</style>"
+      "<style>#stickyParent { position: sticky; top: 0;}"
+      "#stickyGrandchild { position: sticky; top: 0;}</style>"
       "<div id='stickyParent'><div><div id='stickyGrandchild'></div></div>"
       "</div>");
 
@@ -468,8 +483,8 @@ TEST_F(LayoutBoxModelObjectTest,
        StickyPositionFindsCorrectContainingBlockShiftingAncestorTable) {
   setBodyInnerHTML(
       "<style>#scroller { overflow-y: scroll; }"
-      "#stickyOuter { position: sticky; }"
-      "#stickyTh { position: sticky; }</style>"
+      "#stickyOuter { position: sticky; top: 0;}"
+      "#stickyTh { position: sticky; top: 0;}</style>"
       "<div id='scroller'><div id='stickyOuter'><table><thead><tr>"
       "<th id='stickyTh'></th></tr></thead></table></div></div>");
 
@@ -843,10 +858,18 @@ TEST_F(LayoutBoxModelObjectTest, StickyPositionNestedInlineElements) {
       "<style>#scroller { width: 100px; height: 100px; overflow-y: scroll; }"
       "#paddingBefore { height: 50px; }"
       "#outerInline { display: inline; position: sticky; top: 0; }"
+      "#unanchoredSticky { position: sticky; display: inline; }"
       "#innerInline { display: inline; position: sticky; top: 25px; }"
       "#paddingAfter { height: 200px; }</style>"
-      "<div id='scroller'><div id='paddingBefore'></div><div id='outerInline'>"
-      "<div id='innerInline'></div></div><div id='paddingAfter'></div></div>");
+      "<div id='scroller'>"
+      "  <div id='paddingBefore'></div>"
+      "  <div id='outerInline'>"
+      "    <div id='unanchoredSticky'>"
+      "      <div id='innerInline'></div>"
+      "    </div>"
+      "  </div>"
+      "  <div id='paddingAfter'></div>"
+      "</div>");
 
   LayoutBoxModelObject* outerInline =
       toLayoutBoxModelObject(getLayoutObjectByElementId("outerInline"));