After this change, texture_format_map.json maps the GL internal formats
to an enumeration of formats that is internal to ANGLE.

Each ANGLE format specifies a unique combination of DXGI formats and
what type of data the format contains. In the future, the ANGLE format
could be used instead of DXGI format inside C++ code to identify which
type of data a resource contains. This becomes useful when a GL format is
associated with multiple DXGI formats, which may have different type
information (for example depth vs. red, integer vs. float).

texture_format_data.json is changed to only store data on these ANGLE
formats.

BUG=angleproject:1318
BUG=angleproject:1244
TEST=gen_texture_format_table.py (no changes in autogenerated file)

Change-Id: I729c4a4d6fc66ee61598ef2d879e6785c85d40ab
Reviewed-on: https://chromium-review.googlesource.com/328251Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>