Suppress invalid-heap-arg error in pdfium_unittests
Suppress invalid-heap-arg error in pdfium_unittests

Visual Studio sometimes uses new instead of new[] for array allocation,
which causes Dr. Memory report invalid-heap-arg errors.
Suppress such errors since it is not developers' problems.

TBR=tsepez@chromium.org
BUG=pdfium:287

Review URL: https://codereview.chromium.org/1473913002 .

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