[CSS Grid Layout] Rename grid placement properties

Source/core/rendering/style/StyleGridItemData.h

Index: Source/core/rendering/style/StyleGridItemData.h
diff --git a/Source/core/rendering/style/StyleGridItemData.h b/Source/core/rendering/style/StyleGridItemData.h
index d68ffd4e9009145d4bdee2376c267ffa55a00542..76214b52663ec4f046ff7c1f968be4d8cf08bf29 100644
--- a/Source/core/rendering/style/StyleGridItemData.h
+++ b/Source/core/rendering/style/StyleGridItemData.h
@@ -46,8 +46,8 @@ public:
 
     bool operator==(const StyleGridItemData& o) const
     {
-        return m_gridStart == o.m_gridStart && m_gridEnd == o.m_gridEnd
-            && m_gridBefore == o.m_gridBefore && m_gridAfter == o.m_gridAfter;
+        return m_gridColumnStart == o.m_gridColumnStart && m_gridColumnEnd == o.m_gridColumnEnd
+            && m_gridRowStart == o.m_gridRowStart && m_gridRowEnd == o.m_gridRowEnd;
     }
 
     bool operator!=(const StyleGridItemData& o) const
@@ -55,10 +55,10 @@ public:
         return !(*this == o);
     }
 
-    GridPosition m_gridStart;
-    GridPosition m_gridEnd;
-    GridPosition m_gridBefore;
-    GridPosition m_gridAfter;
+    GridPosition m_gridColumnStart;
+    GridPosition m_gridColumnEnd;
+    GridPosition m_gridRowStart;
+    GridPosition m_gridRowEnd;
 
 private:
     StyleGridItemData();