Work around NVIDIA driver issue with glLineWidth(NaN)

Work around NVIDIA driver issue with glLineWidth(NaN)

Set line width to 1.0 in the driver in case line width NaN is requested.

BUG=402847
TEST=WebGL conformance tests

[oetuaho-nv, 2014-08-12 13:39:59]

Please review.

[Zhenyao Mo, 2014-08-12 22:00:47]

On 2014/08/12 13:39:59, oetuaho-nv wrote:
> Please review.

For workarounds, we always use
https://code.google.com/p/chromium/codesearch#chromium/src/gpu/config/gpu_dri...
and
https://code.google.com/p/chromium/codesearch#chromium/src/gpu/config/gpu_dri...
to keep track, so we can turn it off using --disable-gpu-driver-bug-workarounds
for vendors to test their drivers, or to remove it later when the bug is fixed.

[oetuaho-nv, 2014-08-13 10:05:09]

This turned out to not actually be a driver bug. GL spec allows undefined
results when NaN is supplied to a function taking floating point data. I'll
submit an alternate fix that will take care of the GL error leaking.

[Zhenyao Mo, 2014-08-13 19:33:22]

On 2014/08/13 10:05:09, oetuaho-nv wrote:
> This turned out to not actually be a driver bug. GL spec allows undefined
> results when NaN is supplied to a function taking floating point data. I'll
> submit an alternate fix that will take care of the GL error leaking.

WebGL should not have undefined results though.  So maybe we should update the
WebGL spec and consistently generate a INVALID_VALUE error.

+kbr

[Zhenyao Mo, 2014-08-13 19:33:42]

Ken, what do you think about the spec change suggestion?

[Zhenyao Mo, 2014-08-13 19:38:50]

Never mind here, I see your other CL doing this already.