gm: if test has no expectations, record its result as no-expectations regardless of ignoreFailure

gm/tests/outputs/compared-against-empty-dir/output-expected/json-summary.txt

 {
    "actual-results" : {
       "failed" : null,
       "failure-ignored" : null,
       "no-comparison" : {
          "565/selftest1.png" : [ "bitmap-64bitMD5", 12927999507540085554 ],
          "8888/selftest1.png" : [ "bitmap-64bitMD5", 1209453360120438698 ]
       },
       "succeeded" : null
    },
    "expected-results" : {
       "565/selftest1.png" : {
          "allowed-digests" : null,
          "ignore-failure" : false
       },
       "8888/selftest1.png" : {
          "allowed-digests" : null,
-         "ignore-failure" : false
+         "ignore-failure" : true

[epoger, 2013/10/09 19:09:23]

I adjusted this self-test a bit: now, even if the test is marked as
ignore-failure, it still shows up in the no-comparison section of results if
appropriate.

       }
    }
 }