The dynamic buffer we are using in the LineLoopHelper wasn't able
to support switching between different allocation sizes. Fix this by
simply using a min alignment of the maximum allocation size we can
reach.

Adds 2 new tests to validate these calls in StateChangeTest.cpp

Bug: angleproject:2458

Change-Id: I9d224e7dcfcd7627010832ca30dd9e1b9eceea4e
Reviewed-on: https://chromium-review.googlesource.com/1007335
Commit-Queue: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>