This avoids using kTaggedSigned and kTaggedPointer because the
semantic information of those type could be invalid in unreachable
code.

For example, SmiCheck(0.1) has representation TaggedSigned, but it is
later compiled to DeoptimizeUnless(ObjectIsSmi(0.1)) with the constant
0.1 directly connected to the uses. If the use is state-values, which
recorded the TaggedSigned representation of CheckSmi, the code
generator will be confused because it will see constant 0.1 that
claims to be TaggedSigned value.

BUG=chromium:675704

Review-Url: https://codereview.chromium.org/2656243004
Cr-Commit-Position: refs/heads/master@{#42756}