Revert of Re-enable memory.top_7_stress test now that bug 455349 is fixed....

Revert of Re-enable memory.top_7_stress test now that bug 455349 is fixed. (patchset #1 id:1 of https://codereview.chromium.org/940283007/)

Reason for revert:
This is still failing on the bots, with a facebook login failure: http://build.chromium.org/p/chromium.perf/builders/Linux%20Perf%20%283%29/builds/9314/steps/memory.top_7_stress.reference/logs/stdio

Original issue's description:
> Re-enable memory.top_7_stress test now that bug 455349 is fixed.
>
> BUG=459646
>
> Committed: https://crrev.com/92fb7ce426ebe966630fbd0de62e59cee91a6e74
> Cr-Commit-Position: refs/heads/master@{#317606}

TBR=petrcermak@chromium.org,primiano@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=459646

Review URL: https://codereview.chromium.org/942113005

Cr-Commit-Position: refs/heads/master@{#317668}

tools/perf/benchmarks/memory.py

@@ -17,6 +17,7 @@ class MemoryMobile(benchmark.Benchmark):
     return 'memory.mobile_memory'
 
 
+@benchmark.Disabled  # http://crbug.com/459646
 class MemoryTop7Stress(benchmark.Benchmark):
   """Use (recorded) real world web sites and measure memory consumption."""
   test = memory.Memory