[Alignment] Single class for holding the alignment data.

Source/core/style/StyleRareNonInheritedData.h

Index: Source/core/style/StyleRareNonInheritedData.h
diff --git a/Source/core/style/StyleRareNonInheritedData.h b/Source/core/style/StyleRareNonInheritedData.h
index 7b39768e741682a3048472ec2327daba850944e2..e58b9706e46ab11c3de4dd7f4da529e09cc17337 100644
--- a/Source/core/style/StyleRareNonInheritedData.h
+++ b/Source/core/style/StyleRareNonInheritedData.h
@@ -36,6 +36,7 @@
 #include "core/style/LineClampValue.h"
 #include "core/style/NinePieceImage.h"
 #include "core/style/ShapeValue.h"
+#include "core/style/StyleAlignmentData.h"
 #include "platform/LengthPoint.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassRefPtr.h"
@@ -150,16 +151,10 @@ public:
     unsigned m_transformStyle3D : 1; // ETransformStyle3D
     unsigned m_backfaceVisibility : 1; // EBackfaceVisibility
 
-    unsigned m_alignContent : 4; // ContentPosition
-    unsigned m_alignContentDistribution : 3; // ContentDistributionType
-    unsigned m_alignContentOverflowAlignment : 2; // OverflowAlignment
-    unsigned m_alignItems : 4; // ItemPosition
-    unsigned m_alignItemsOverflowAlignment : 2; // OverflowAlignment
-    unsigned m_alignSelf : 4; // ItemPosition
-    unsigned m_alignSelfOverflowAlignment : 2; // OverflowAlignment
-    unsigned m_justifyContent : 4; // ContentPosition
-    unsigned m_justifyContentDistribution : 3; // ContentDistributionType
-    unsigned m_justifyContentOverflowAlignment : 2; // OverflowAlignment
+    StyleAlignmentData m_alignContent;
+    StyleAlignmentData m_alignItems;
+    StyleAlignmentData m_alignSelf;
+    StyleAlignmentData m_justifyContent;
 
     unsigned userDrag : 2; // EUserDrag
     unsigned textOverflow : 1; // Whether or not lines that spill out should be truncated with "..."
@@ -187,12 +182,9 @@ public:
 
     unsigned m_isolation : 1; // Isolation
 
-    unsigned m_justifyItems : 4; // ItemPosition
-    unsigned m_justifyItemsOverflowAlignment : 2; // OverflowAlignment
-    unsigned m_justifyItemsPositionType: 1; // Whether or not alignment uses the 'legacy' keyword.
+    StyleAlignmentData m_justifyItems;
 
-    unsigned m_justifySelf : 4; // ItemPosition
-    unsigned m_justifySelfOverflowAlignment : 2; // OverflowAlignment
+    StyleAlignmentData m_justifySelf;
 
     // ScrollBehavior. 'scroll-behavior' has 2 accepted values, but ScrollBehavior has a third
     // value (that can only be specified using CSSOM scroll APIs) so 2 bits are needed.