Suppress all conformance/textures/canvas_sub_rectangle/* on Mac NVidia

There is a known failure mode for these tests on Mac NVidia, with finding
a fix de-prioritized due to general WebGL2 conformance issue on Mac.

I'm expanding the suppression to include the other tests in that folder
as currently 10% of runs on the Mac NVidia bot fail due to one of them.

TBR=ynovikov@chromium.org
TEST=conformance/textures/canvas_sub_rectangle/*

Bug: 1027776
Change-Id: I1df617130b30d27fb13efac165ab7df2d9bfb2c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231548Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775302}

content/test/gpu/gpu_tests/test_expectations/webgl2_conformance_expectations.txt

@@ -443,7 +443,7 @@ crbug.com/1027776 [ mac nvidia-0xfe9 ] deqp/data/gles3/shaders/conversions.html
 crbug.com/1027776 [ mac nvidia-0xfe9 ] conformance2/rendering/framebuffer-texture-level1.html [ Failure ]
 crbug.com/1037650 [ mac nvidia-0xfe9 ] conformance2/textures/canvas_sub_rectangle/* [ RetryOnFailure ]
 crbug.com/1073538 [ mac nvidia-0xfe9 ] deqp/functional/gles3/shadermatrix/div_dynamic.html [ RetryOnFailure ]
-crbug.com/1086194 [ mac nvidia-0xfe9 ] conformance/textures/canvas_sub_rectangle/tex-2d-rgb-rgb-unsigned_byte.html [ RetryOnFailure ]
+crbug.com/1086194 [ mac nvidia-0xfe9 ] conformance/textures/canvas_sub_rectangle/* [ RetryOnFailure ]
 
 # Mac AMD
 # TODO(kbr): uncomment the following two exepectations after test