The Tracing split CL https://codereview.chromium.org/1707563002 mostly moved the location of
the TRACE call, but it added 2 very high frequency calls related to tracking V8.External.

In most benchmark and devices the added overhead is negligible except on N6 where it gets amplified.
This CL removes those 2 calls until more efficient tracing or a different technique is used.

BUG=588137
LOG=N

Review URL: https://codereview.chromium.org/1765673003

Cr-Commit-Position: refs/heads/master@{#34499}