Adapt and reland old position sticky implementation

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

Index: third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp b/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
index 9cb0abffa3efaf13210faa2fc3893274ad9efdbc..a50e90597ccf64ec8477691147a3cba62bf81adc 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
@@ -105,6 +105,10 @@ void LayoutGeometryMap::mapToAncestor(TransformState& transformState, const Layo
             ASSERT(currentStep.m_layoutObject->isLayoutView());
             transformState.move(currentStep.m_offsetForFixedPosition);
         }
+        if (!currentStep.m_offsetForStickyPosition.isZero()) {
+            ASSERT(currentStep.m_layoutObject->style()->position() == StickyPosition);
+            transformState.move(currentStep.m_offsetForStickyPosition);
+        }
     }
 
     ASSERT(foundAncestor);
@@ -218,33 +222,37 @@ void LayoutGeometryMap::pushMappingsToAncestor(const PaintLayer* layer, const Pa
     pushMappingsToAncestor(layoutObject, ancestorLayoutObject);
 }
 
-void LayoutGeometryMap::push(const LayoutObject* layoutObject, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void LayoutGeometryMap::push(const LayoutObject* layoutObject, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition, LayoutSize offsetForStickyPosition)
 {
     LAYOUT_GEOMETRY_MAP_LOG("LayoutGeometryMap::push %p %d,%d isNonUniform=%d\n", layoutObject, offsetFromContainer.width().toInt(), offsetFromContainer.height().toInt(), isNonUniform);
 
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!layoutObject->isLayoutView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
     ASSERT(offsetForFixedPosition.isZero() || layoutObject->isLayoutView());
+    ASSERT(offsetForStickyPosition.isZero() || layoutObject->style()->position() == StickyPosition);
 
     m_mapping.insert(m_insertionPosition, LayoutGeometryMapStep(layoutObject, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
 
     LayoutGeometryMapStep& step = m_mapping[m_insertionPosition];
     step.m_offset = offsetFromContainer;
     step.m_offsetForFixedPosition = offsetForFixedPosition;
+    step.m_offsetForStickyPosition = offsetForStickyPosition;
 
     stepInserted(step);
 }
 
-void LayoutGeometryMap::push(const LayoutObject* layoutObject, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void LayoutGeometryMap::push(const LayoutObject* layoutObject, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition, LayoutSize offsetForStickyPosition)
 {
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!layoutObject->isLayoutView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
     ASSERT(offsetForFixedPosition.isZero() || layoutObject->isLayoutView());
+    ASSERT(offsetForStickyPosition.isZero() || layoutObject->style()->position() == StickyPosition);
 
     m_mapping.insert(m_insertionPosition, LayoutGeometryMapStep(layoutObject, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
 
     LayoutGeometryMapStep& step = m_mapping[m_insertionPosition];
     step.m_offsetForFixedPosition = offsetForFixedPosition;
+    step.m_offsetForStickyPosition = offsetForStickyPosition;
 
     if (!t.isIntegerTranslation())
         step.m_transform = adoptPtr(new TransformationMatrix(t));