The pointer from vector::data() already reflects the size of the
underlying type, so no need to include sizeof.  This caused us to
write beyond the vector bounds when reading multiple values.

We were also missing component count.

Test: MEC of NBA2K20
Bug: b/160014453
Change-Id: I51fc3f5f80c732221d6ea4b4bd1afde635e410a1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2270909Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Manh Nguyen <nguyenmh@google.com>
Commit-Queue: Cody Northrop <cnorthrop@google.com>