Second round of GPU gradient rebaselines

expectations/gm/Test-Win7-ShuttleA-HD2000-x86-Debug/expected-results.json

 {
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   "expected-results": {
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       "allowed-digests": [
@@ skipping 9657 matching lines @@
       ], 
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       ], 
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     "srcmode_gpu.png": {
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           "bitmap-64bitMD5", 
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+          248128091148658883
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     "srcmode_pdf-poppler.png": {
       "allowed-digests": [
         [
@@ skipping 1111 matching lines @@
           9206571293968307032
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 }