This mjsunittest assumed specific internal types (i.e. Smi)
for certain fields; it generates some dozens of variants of
the test using new Function, but used the same property names
in all of them. This causes V8 to sometimes learn more general
types for fields (i.e. unboxed double), which the test did not
expect. This commit uses unique field names for each of the test
variants.


Change-Id: Ib1ecb3ae33a57c8a1293a29a2233dad4e16a39fb
Reviewed-on: https://chromium-review.googlesource.com/1004897
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52528}