Don't let PaintInvalidationLocationChange shadow other reasons

third_party/WebKit/LayoutTests/compositing/squashing/add-remove-squashed-layers-expected.txt

 Test that layers can be nicely added or removed from a squashed layer, without unnecessary repaints on any layer. Click anywhere to test interactively; keep clicking to proceed through the test.
 
 CASE 1, original layer tree with overlap1 and overlap2:
 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
@@ skipping 45 matching lines @@
               "backgroundColor": "#808080"
             },
             {
               "position": [140, 140],
               "bounds": [260, 260],
               "drawsContent": true,
               "paintInvalidations": [
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='C' class='overlap3'",
                   "rect": [160, 160, 100, 100],
-                  "reason": "location change"
+                  "reason": "layoutObject insertion"
                 }
               ]
             }
           ]
         }
       ]
     }
   ]
 }
 CASE 3, overlap2 gets removed. Since this does not resize the layer, there should only be a repaint of overlap2:
@@ skipping 63 matching lines @@
                   "reason": "layer"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='A' class='overlap1'",
                   "rect": [0, 0, 100, 100],
                   "reason": "layoutObject removal"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='C' class='overlap3'",
                   "rect": [0, 0, 100, 100],
-                  "reason": "location change"
+                  "reason": "compositing update"
                 }
               ]
             }
           ]
         }
       ]
     }
   ]
 }
 CASE 5, overlap2 gets added back:
@@ skipping 22 matching lines @@
               "backgroundColor": "#808080"
             },
             {
               "position": [220, 220],
               "bounds": [180, 180],
               "drawsContent": true,
               "paintInvalidations": [
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='C' class='overlap3'",
                   "rect": [80, 80, 100, 100],
-                  "reason": "location change"
+                  "reason": "compositing update"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='B' class='overlap2'",
                   "rect": [0, 0, 100, 100],
                   "reason": "layoutObject insertion"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='C' class='overlap3'",
                   "rect": [0, 0, 100, 100],
                   "reason": "layer"
@@ skipping 32 matching lines @@
               "backgroundColor": "#808080"
             },
             {
               "position": [140, 140],
               "bounds": [180, 180],
               "drawsContent": true,
               "paintInvalidations": [
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='B' class='overlap2'",
                   "rect": [80, 80, 100, 100],
-                  "reason": "location change"
+                  "reason": "compositing update"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='C' class='overlap3'",
                   "rect": [80, 80, 100, 100],
                   "reason": "layoutObject removal"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='A' class='overlap1'",
                   "rect": [0, 0, 100, 100],
                   "reason": "layoutObject insertion"
                 },
                 {
                   "object": "LayoutBlockFlow (positioned) DIV id='B' class='overlap2'",
                   "rect": [0, 0, 100, 100],
                   "reason": "layer"
                 }
               ]
             }
           ]
         }
       ]
     }
   ]
 }