Collapse whitespace away when creating whitespace layout objects.

third_party/WebKit/LayoutTests/paint/invalidation/compositing/remove-squashed-layer-plus-move-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [1418, 1008],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow DIV id='container'",
@@ skipping 88 matching lines @@
       "object": "RootInlineBox",
       "reason": "bounds change"
     },
     {
       "object": "LayoutBlockFlow (relative positioned) DIV class='mv-tile'",
       "reason": "compositing update"
     },
     {
       "object": "LayoutText #text",
       "reason": "location change"
-    },
-    {
-      "object": "LayoutText #text",
-      "reason": "location change"
     }
   ]
 }