Update VectorConstructor unit test with mixed-type ctors.

GLSL allows mixed types inside a vector constructor, but SkSL currently
doesn't handle it well; some cases don't compile, and others generate
bad code. This will be fixed in a followup CL.

Change-Id: Ia98b498f320b8fa91595404730f6cdc836615140
Bug: skia:11164
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/353577
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
8 files changed