This is a mechanical change. Similar to constructor, the reset()
function is doing initialization of data members. Move them next to each
other helps adding a new data members which requires modifications to
both functions.

Bug: b/175584609
Change-Id: I11386677bc5c9838104025d6a4ecf6f2b58fa92c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2745842Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Commit-Queue: Charlie Lao <cclao@google.com>