Remove two uses of setModifiersHandle

As a prelude to going back to sharing global data (safely), we want to
eliminate as much mutation of shared state as possible. The special
cases for global variable declaration were unnecessary, so just remove
them. The editing of main's parameters immediately after they were
created is also unnecessary - just hoist the logic up so we create the
variables correctly in the first place.

There is still one use, related to invocation ID. That's more
complicated (?), so leaving it as a separate CL.

Change-Id: Ia3dad78dd5a634273b2e2239368be7adaff65f38
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325661
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
8 files changed