Adds 'flex' and 'inline-flex' as a display value

Change-Id: Ic1159319b03020f6645434fe10de57a5310ac30f
diff --git a/user/src/com/google/gwt/dom/client/Style.java b/user/src/com/google/gwt/dom/client/Style.java
index fe583ec..4bf32fc 100644
--- a/user/src/com/google/gwt/dom/client/Style.java
+++ b/user/src/com/google/gwt/dom/client/Style.java
@@ -387,6 +387,18 @@
       public String getCssName() {
         return DISPLAY_INITIAL;
       }
+    },
+    FLEX {
+      @Override
+      public String getCssName() {
+        return DISPLAY_FLEX;
+      }
+    },
+    INLINE_FLEX {
+      @Override
+      public String getCssName() {
+        return DISPLAY_INLINE_FLEX;
+      }
     };
     @Override
     public abstract String getCssName();
@@ -1019,6 +1031,8 @@
   private static final String DISPLAY_TABLE_COLUMN = "table-column";
   private static final String DISPLAY_TABLE_ROW = "table-row";
   private static final String DISPLAY_INITIAL = "initial";
+  private static final String DISPLAY_FLEX = "flex";
+  private static final String DISPLAY_INLINE_FLEX = "inline-flex";
 
   private static final String FLOAT_LEFT = "left";
   private static final String FLOAT_RIGHT = "right";