Mark conformance2/textures/canvas_sub_rectangle/* flaky on Linux NVIDIA.

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

Index: content/test/gpu/gpu_tests/webgl2_conformance_expectations.py
diff --git a/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py b/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py
index 496c156ab17baf18217ee26651e406ff190cda37..f628257c163c8193d1e03e8ace4352411d4ad320 100644
--- a/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py
+++ b/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py
@@ -719,6 +719,12 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
     self.Flaky('deqp/functional/gles3/multisample.html',
         ['linux', ('nvidia', 0x104a)], bug=714207)
 
+    # Any of these tests become flaky if they follow
+    # conformance2/samplers/samplers.html and if virtualized GL
+    # contexts are being used.
+    self.Flaky('conformance2/textures/canvas_sub_rectangle/*',
+        ['linux', 'nvidia'], bug=694359)
+
     # This test is flaky both with and without ANGLE.
     self.Flaky('deqp/functional/gles3/texturespecification/' +
         'random_teximage2d_2d.html',