[crosperf] Fix default result for smoothness.tough_webgl_cases.

The name of the default summary field for this test has changed,
which makes crosperf fail since it can't find the right result
field.  This CL fixes that problem.

BUG=None
TEST=Tested with nightly testd on chrotomation2.

Change-Id: I049c8abd2dd30b64aec8be65feb56b31115a4921
Reviewed-on: https://chrome-internal-review.googlesource.com/249130
Commit-Ready: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
Reviewed-by: Yunlian Jiang <yunlian@google.com>
1 file changed