Fix incorrect rebaseline of one test (contentsOpaque should be false).

third_party/WebKit/LayoutTests/paint/invalidation/background-resize-height-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image'",
       "position": [8, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image'",
           "rect": [0, 40, 60, 4],
           "reason": "incremental"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image size-cover'",
       "position": [58, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image size-cover'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image size-contain'",
       "position": [108, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image size-contain'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image fixed-height'",
       "position": [158, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image fixed-height'",
           "rect": [0, 40, 60, 4],
           "reason": "incremental"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image percent-height'",
       "position": [208, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image percent-height'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image top'",
       "position": [258, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image top'",
           "rect": [0, 40, 60, 4],
           "reason": "incremental"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image bottom'",
       "position": [308, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image bottom'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image center'",
       "position": [358, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image center'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
@@ skipping 22 matching lines @@
           "object": "LayoutBlockFlow (positioned) DIV class='test image repeat-space'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
     {
       "name": "LayoutBlockFlow (positioned) DIV class='test image repeat-round'",
       "position": [508, 8],
       "bounds": [60, 44],
-      "contentsOpaque": true,
       "drawsContent": true,
       "backfaceVisibility": "hidden",
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV class='test image repeat-round'",
           "rect": [0, 0, 60, 44],
           "reason": "border box change"
         }
       ]
     },
@@ skipping 246 matching lines @@
       "object": "LayoutBlockFlow (positioned) DIV class='test generated repeat-space'",
       "reason": "border box change"
     },
     {
       "object": "LayoutBlockFlow (positioned) DIV class='test generated repeat-round'",
       "reason": "border box change"
     }
   ]
 }