Make invokeChild default to fInputColor, rather than half4(1)

By extension, this changes the default behavior of sample() in .fp
files. This lets us remove the explicit fInputColor/sk_InColor
arguments everywhere. Most sites that were using the default no
longer care what's passed, as the child is known to be a texture
effect that will ignore the input color. The few remaining sites
now explicitly pass half4(1) when necessary.

Change-Id: Ie4691b049f905d098e9befe8bd07706a496f2968
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/303356
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
49 files changed