Fix point conversions in PopupContainer.

Source/web/PopupContainer.cpp

Index: Source/web/PopupContainer.cpp
diff --git a/Source/web/PopupContainer.cpp b/Source/web/PopupContainer.cpp
index 35e901c5dbe44bff5bb384d306bc80ed3f159074..a2bcd15b02feb3f6e9924ef04c94636963870fb8 100644
--- a/Source/web/PopupContainer.cpp
+++ b/Source/web/PopupContainer.cpp
@@ -525,4 +525,18 @@ HostWindow* PopupContainer::hostWindow() const
     return const_cast<PopupContainerClient*>(m_client);
 }
 
+IntPoint PopupContainer::convertChildToSelf(const Widget* child, const IntPoint& point) const
+{
+    IntPoint newPoint = point;
+    newPoint.moveBy(child->location());
+    return newPoint;
+}
+
+IntPoint PopupContainer::convertSelfToChild(const Widget* child, const IntPoint& point) const
+{
+    IntPoint newPoint = point;
+    newPoint.moveBy(-child->location());
+    return newPoint;
+}
+
 } // namespace blink