Avoid building blink_heap_unittests to unblock the Blink roll
Avoid building blink_heap_unittests to unblock the Blink roll

The test is brand-new and is the only user of the code that's causing
link errors on GCC/component build.

BUG=332220
TBR=vegorov@chromium.org

Review URL: https://codereview.chromium.org/127063002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@164638 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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