Materializing all variables should be done prior to actual branches, not
when changing the insert point. The only reason we did it in the latter
too was due to changing insert point before creating the branch for an
If statement.

Bug: b/180131694
Change-Id: Ic755bf07a098bda4af7e4d5a7d22138bee37d0c6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52968Tested-by: Nicolas Capens <nicolascapens@google.com>
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>