Add limited support for parsing array constructors and writing them out as
GLSL code.

Still missing from this version: HLSL output, array support in
initializer lists, arrays with implicit size.

BUG=angleproject:941

Change-Id: I7febf80923c4cd0b730399f1f49f9456cf3668e9
Reviewed-on: https://chromium-review.googlesource.com/260572Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>