Revert "Use scratch keys for stencil buffers."

expectations/gm/Test-Android-GalaxyS4-SGX544-Arm7-Release/expected-results.json

 {
   "actual-results": {
     "failed": null, 
     "failure-ignored": null, 
     "no-comparison": null, 
     "succeeded": null
   }, 
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
@@ skipping 3839 matching lines @@
           "bitmap-64bitMD5", 
           7505650564332324157
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "drrect_gpu.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          18165407505633347407
+          4938590834664658305
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "emboss_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           11734805616328532473
         ]
@@ skipping 1966 matching lines @@
           "bitmap-64bitMD5", 
           357284903731074601
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "imageblur2_gpu.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          2311109700305266403
+          167979044054175148
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "imageblur_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           13620335786972140736
         ]
@@ skipping 97 matching lines @@
           "bitmap-64bitMD5", 
           4262113639047937913
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "imagefiltersbase_gpu.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          5148862615526465916
+          9298514044054867967
         ]
       ], 
       "ignore-failure": false, 
       "reviewed-by-human": true
     }, 
     "imagefiltersclipped_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           9643897842146508458
@@ skipping 4002 matching lines @@
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           6723019659179571394
         ]
       ], 
       "reviewed-by-human": false
     }
   }
 }