[X86] Fix compile time regression of D93594.

D93594 depend on the dominate tree and loop information. It increased
the compile time when build with -O0. However this is just to amend the
dominate tree and loop information, so that it is unnecessary to
re-analyze them again. Given the dominate tree of loop information are
absent in this pass, we can avoid amending them.

Differential Revision: https://reviews.llvm.org/D98773