Add localToAbsoluteTransform and localToAncestorTransform.

third_party/WebKit/Source/platform/geometry/TransformState.cpp

Index: third_party/WebKit/Source/platform/geometry/TransformState.cpp
diff --git a/third_party/WebKit/Source/platform/geometry/TransformState.cpp b/third_party/WebKit/Source/platform/geometry/TransformState.cpp
index 9ec2073661391dd75f49b5aa40f7459213729c7b..c119f0f8d48cfd1b8afb73dfd88b92288aa34bff 100644
--- a/third_party/WebKit/Source/platform/geometry/TransformState.cpp
+++ b/third_party/WebKit/Source/platform/geometry/TransformState.cpp
@@ -39,6 +39,7 @@ TransformState& TransformState::operator=(const TransformState& other)
     if (m_mapQuad)
         m_lastPlanarQuad = other.m_lastPlanarQuad;
     m_accumulatingTransform = other.m_accumulatingTransform;
+    m_forceAccumulatingTransform = other.m_forceAccumulatingTransform;
     m_direction = other.m_direction;
 
     m_accumulatedTransform.clear();
@@ -68,6 +69,9 @@ void TransformState::translateMappedCoordinates(const LayoutSize& offset)
 
 void TransformState::move(const LayoutSize& offset, TransformAccumulation accumulate)
 {
+    if (m_forceAccumulatingTransform)
+        accumulate = AccumulateTransform;
+
     if (accumulate == FlattenTransform || !m_accumulatedTransform) {
         m_accumulatedOffset += offset;
     } else {
@@ -127,14 +131,19 @@ void TransformState::applyTransform(const TransformationMatrix& transformFromCon
     }
 
     if (accumulate == FlattenTransform) {
-        const TransformationMatrix* finalTransform = m_accumulatedTransform ? m_accumulatedTransform.get() : &transformFromContainer;
-        flattenWithTransform(*finalTransform, wasClamped);
+        if (m_forceAccumulatingTransform) {
+            m_accumulatedTransform->flattenTo2d();
+        } else {
+            const TransformationMatrix* finalTransform = m_accumulatedTransform ? m_accumulatedTransform.get() : &transformFromContainer;
+            flattenWithTransform(*finalTransform, wasClamped);
+        }
     }
-    m_accumulatingTransform = accumulate == AccumulateTransform;
+    m_accumulatingTransform = accumulate == AccumulateTransform || m_forceAccumulatingTransform;
 }
 
 void TransformState::flatten(bool* wasClamped)
 {
+    ASSERT(!m_forceAccumulatingTransform);
     if (wasClamped)
         *wasClamped = false;
 
@@ -180,6 +189,12 @@ FloatQuad TransformState::mappedQuad(bool* wasClamped) const
     return m_accumulatedTransform->inverse().projectQuad(quad, wasClamped);
 }
 
+const TransformationMatrix& TransformState::accumulatedTransform() const
+{
+    ASSERT(m_forceAccumulatingTransform && m_accumulatingTransform);
+    return *m_accumulatedTransform;
+}
+
 void TransformState::flattenWithTransform(const TransformationMatrix& t, bool* wasClamped)
 {
     if (m_direction == ApplyTransformDirection) {