Don't let PaintInvalidationLocationChange shadow other reasons

third_party/WebKit/LayoutTests/platform/linux/fast/repaint/line-flow-with-floats-9-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow P",
           "rect": [8, 80, 418, 519],
           "reason": "invalidate paint rectangle"
         },
         {
           "object": "LayoutBlockFlow (floating) SPAN id='yellowFloat'",
           "rect": [372, 243, 48, 49],
-          "reason": "location change"
+          "reason": "layoutObject insertion"
         },
         {
           "object": "LayoutText #text",
           "rect": [420, 240, 1, 139],
           "reason": "incremental"
         },
         {
           "object": "InlineTextBox ' twist itself round and look up in her'",
           "reason": "full"
         },
@@ skipping 335 matching lines @@
         },
         {
           "object": "RootInlineBox",
           "reason": "full"
         }
       ]
     }
   ]
 }