Revert "[LowerTypeTests] Avoid creation of select constant expression"

This reverts commit 0317147a.

It causes broken module error when building chromium media_unittests
PHI nodes not grouped at top of basic block!
%19 = phi ptr [ %16, %15 ], [ %18, %12 ], !dbg !16
label %17
LLVM ERROR: Broken module found, compilation aborted!