Bug 1000376 - part 1, Add -moz-anonymous-grid-item in the style system. r=dholbert

layout/style/nsCSSAnonBoxList.h

@@ -62,10 +62,14 @@ CSS_ANON_BOX(columnContent, ":-moz-column-content")
 CSS_ANON_BOX(viewport, ":-moz-viewport")
 CSS_ANON_BOX(viewportScroll, ":-moz-viewport-scroll")
 
-// Inside a flex container, a contiguous run of non-replaced inline children
-// gets wrapped in an anonymous block, which is then treated as a flex item.
+// Inside a flex container, a contiguous run of text gets wrapped in
+// an anonymous block, which is then treated as a flex item.
 CSS_ANON_BOX(anonymousFlexItem, ":-moz-anonymous-flex-item")
 
+// Inside a grid container, a contiguous run of text gets wrapped in
+// an anonymous block, which is then treated as a grid item.
+CSS_ANON_BOX(anonymousGridItem, ":-moz-anonymous-grid-item")
+
 #ifdef MOZ_XUL
 CSS_ANON_BOX(moztreecolumn, ":-moz-tree-column")
 CSS_ANON_BOX(moztreerow, ":-moz-tree-row")

layout/style/ua.css

@@ -181,9 +181,10 @@
   height: 100%;
 }
 
-*|*::-moz-anonymous-flex-item {
-  /* Anonymous blocks that wrap contiguous runs of inline non-replaced
-   * content inside of a flex container. */
+*|*::-moz-anonymous-flex-item,
+*|*::-moz-anonymous-grid-item {
+  /* Anonymous blocks that wrap contiguous runs of text
+   * inside of a flex or grid container. */
   display: block;
 }