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 ca3bd92df2e3316f1b930dad517d4e557e0961c8..0f6ba900566200e11a9216fb33d87a75e224cd12 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp
@@ -98,6 +98,10 @@ void LayoutGeometryMap::mapToContainer(TransformState& transformState, const Lay
             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(foundContainer);
@@ -124,7 +128,6 @@ void LayoutGeometryMap::dumpSteps() const
 FloatQuad LayoutGeometryMap::mapToContainer(const FloatRect& rect, const LayoutBoxModelObject* container) const
 {
     FloatQuad result;
-
     if (!hasFixedPositionStep() && !hasTransformStep() && !hasNonUniformStep() && (!container || (m_mapping.size() && container == m_mapping[0].m_layoutObject))) {
         result = rect;
         result.move(m_accumulatedOffset);
@@ -217,33 +220,37 @@ 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)
 {
 //    fprintf(stderr, "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));