Fix pixel snapping issues when layers become composited

Source/platform/geometry/LayoutSize.h

Index: Source/platform/geometry/LayoutSize.h
diff --git a/Source/platform/geometry/LayoutSize.h b/Source/platform/geometry/LayoutSize.h
index 1d0e94c3aa3aacf7f10ada632f76e586d91e3d7e..c950cf535102e968382ba618cd2751e40376812b 100644
--- a/Source/platform/geometry/LayoutSize.h
+++ b/Source/platform/geometry/LayoutSize.h
@@ -126,6 +126,11 @@ public:
         return LayoutSize(width(), width() * aspectRatio.height() / aspectRatio.width());
     }
 
+    LayoutSize fraction() const
+    {
+        return LayoutSize(m_width.fraction(), m_height.fraction());
+    }
+
 private:
     LayoutUnit m_width, m_height;
 };