Reason for revert:
Need to revert previous CL because of Android compile error, and this one depends in it.
Original issue's description:
> [base] Define CHECK comparison for signed vs. unsigned
>
> The current CHECK/DCHECK implementation fails statically if a signed
> value is compared against an unsigned value. The common solution is to
> cast on each caller, which is tedious and error-prone (might hide bugs).
> This CL implements signed vs. unsigned comparisons by executing up to
> two comparisons. For example, if i is int32_t and u is uint_32_t, a
> DCHECK_LE(i, u) would create the check
> i <= 0 || static_cast<uint32_t>(i) <= u.
> For checks against constants, at least one of the checks can be removed
> by compiler optimizations.
>
> The tradeoff we have to make is to sometimes silently execute an
> additional comparison. And we increase code complexity of course, even
> though the usage is just as easy (or even easier) as before.
>
> The compile time impact seems to be minimal:
> I ran 3 full compilations for Optdebug on my local machine, one time on
> the current ToT, one time with this CL plus http://crrev.com/2524093002.
> Before: 143.72 +- 1.21 seconds
> Now: 144.18 +- 0.67 seconds
>
> In order to check that the new comparisons are working, I refactored
> some DCHECKs in wasm to use the new magic.
>
> R=bmeurer@chromium.org, titzer@chromium.org
>
> Committed: https://crrev.com/5925074a9dab5a8577766545b91b62f2c531d3dc
> Cr-Commit-Position: refs/heads/master@{#41275}
TBR=ishell@chromium.org,titzer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review-Url: https://codereview.chromium.org/2531533003
Cr-Commit-Position: refs/heads/master@{#41277}
0406620c6c