failed gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_transform_feedback_switching_objects on on NVIDIA GPU on Mac Retina on Mac-10.12.6

both Mac FYI Retina Release (NVIDIA) https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac%20FYI%20Retina%20Release%20%28NVIDIA%29?limit=50
and Mac FYI Experimental Retina Release (NVIDIA) https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac%20FYI%20Experimental%20Retina%20Release%20%28NVIDIA%29?limit=100

[48/138] gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_transform_feedback_switching_objects failed unexpectedly 3.0613s:
  
  Traceback (most recent call last):
    _RunGpuTest at content/test/gpu/gpu_tests/gpu_integration_test.py:132
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:204
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:218
      self._CheckTestCompletion()
    _CheckTestCompletion at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:214
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module/lib/python2.7/unittest/case.py:410
      raise self.failureException(msg)
  AssertionError: buffer should match expected values
  FAIL buffer should match expected values
  buffer should match expected values
  FAIL buffer should match expected values
  buffer should match expected values
  FAIL buffer should match expected values
  getError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode
  FAIL getError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode
  
  Locals:
    msg : u'buffer should match expected values\nFAIL buffer should match expected values\nbuffer should match expected values\nFAIL buffer should match expected values\nbuffer should match expected values\nFAIL buffer should match expected values\ngetError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode\nFAIL getError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode\n'
  
  Found crashpad_database_util
  No minidump found via crashpad_database_util
  No minidump paths to symbolize
  Found crashpad_database_util
  No minidump found via crashpad_database_util
  Restarting browser due to unexpected test failure
  Closing browser (pid=12256) ...
  Browser is closed.
  Starting Chrome ['/b/s/w/ir/out/Release/Chromium.app/Contents/MacOS/Chromium', '--disable-gpu-watchdog', '--enable-experimental-web-platform-features', '--test-type=gpu', '--disable-domain-blocking-for-3d-apis', '--disable-gpu-process-crash-limit', '--js-flags=--expose-gc', '--enable-logging=stderr', '--autoplay-policy=no-user-gesture-required', '--use-cmd-decoder=validating', '--enable-net-benchmarking', '--metrics-recording-only', '--no-default-browser-check', '--no-first-run', '--enable-gpu-benchmarking', '--deny-permission-prompts', '--autoplay-policy=no-user-gesture-required', '--disable-background-networking', '--disable-component-extensions-with-background-pages', '--disable-default-apps', '--disable-search-geolocation-disclosure', '--proxy-server=socks://localhost:51194', '--ignore-certificate-errors-spki-list=PhrPvGIaAMmd29hj8BCZOq096yj7uMpRNHpn5PDxI6I=', '--remote-debugging-port=0', '--enable-crash-reporter-for-testing', '--disable-component-update', '--window-size=1280,1024', '--user-data-dir=/b/s/w/itCWGDvz/tmpAD1ogk', 'about:blank']
  DoNothingForwarder started between 127.0.0.1:51270 and 51270
  Got devtools config: ws://127.0.0.1:51270/devtools/browser/3c2b47ee-b219-4c2b-a68a-a351c3e4048a
  Browser started (pid=12275).
  OS: mac sierra
  Detailed OS version: 10.12.6 16G29
  Model: MacBookPro 11.3
  Browser command line: /b/s/w/ir/out/Release/Chromium.app/Contents/MacOS/Chromium --disable-gpu-watchdog --enable-experimental-web-platform-features --test-type=gpu --disable-domain-blocking-for-3d-apis --disable-gpu-process-crash-limit --js-flags=--expose-gc --enable-logging=stderr --autoplay-policy=no-user-gesture-required --use-cmd-decoder=validating --enable-net-benchmarking --metrics-recording-only --no-default-browser-check --no-first-run --enable-gpu-benchmarking --deny-permission-prompts --autoplay-policy=no-user-gesture-required --disable-background-networking --disable-component-extensions-with-background-pages --disable-default-apps --disable-search-geolocation-disclosure --proxy-server=socks://localhost:51194 --ignore-certificate-errors-spki-list=PhrPvGIaAMmd29hj8BCZOq096yj7uMpRNHpn5PDxI6I= --remote-debugging-port=0 --enable-crash-reporter-for-testing --disable-component-update --window-size=1280,1024 --user-data-dir=/b/s/w/itCWGDvz/tmpAD1ogk --flag-switches-begin --flag-switches-end about:blank
  GPU device 0: VENDOR = 0x10de (Nvidia), DEVICE = 0xfe9
  GPU device 1: VENDOR = 0x8086 (Intel), DEVICE = 0xd26
  GPU Attributes:
    amd_switchable      : False
    can_support_threaded_texture_mailbox: False
    direct_composition  : False
    direct_rendering    : True
    driver_date         : 
    driver_vendor       : 
    driver_version      : 
    encrypted_only      : False
    gl_extensions       : 
    gl_renderer         : 
    gl_reset_notification_strategy: 0
    gl_vendor           : 
    gl_version          : 
    gl_ws_extensions    : 
    gl_ws_vendor        : 
    gl_ws_version       : 
    in_process_gpu      : False
    initialization_time : 0.150024
    jpeg_decode_accelerator_supported: False
    max_framerate_denominator: 1
    max_framerate_numerator: 30
    max_msaa_samples    : 
    max_resolution_height: 2160
    max_resolution_width: 4096
    min_resolution_height: 16
    min_resolution_width: 16
    optimus             : True
    passthrough_cmd_decoder: False
    pixel_shader_version: 
    process_crash_count : 0
    profile             : 3
    sandboxed           : True
    software_rendering  : False
    supports_overlays   : False
    vertex_shader_version: 
    video_decode_accelerator_flags: 0
  Feature Status:
    2d_canvas           : enabled
    checker_imaging     : enabled_on
    flash_3d            : enabled
    flash_stage3d       : enabled
    flash_stage3d_baseline: enabled
    gpu_compositing     : enabled
    multiple_raster_threads: enabled_on
    native_gpu_memory_buffers: enabled
    rasterization       : enabled
    surface_synchronization: enabled_on
    video_decode        : enabled
    viz_display_compositor: disabled_off
    webgl               : enabled
    webgl2              : enabled
  Driver Bug Workarounds:
    add_and_true_to_loop_condition
    adjust_src_dst_region_for_blitframebuffer
    avoid_stencil_buffers
    decode_encode_srgb_for_generatemipmap
    disable_framebuffer_cmaa
    disable_webgl_rgb_multisampling_usage
    dont_use_loops_to_initialize_variables
    emulate_abs_int_function
    get_frag_data_info_bug
    init_two_cube_map_levels_before_copyteximage
    msaa_is_slow
    pack_parameters_workaround_with_pack_buffer
    rebind_transform_feedback_before_resume
    regenerate_struct_names
    remove_invariant_and_centroid_for_essl3
    reset_teximage2d_base_level
    rewrite_texelfetchoffset_to_texelfetch
    scalarize_vec_and_mat_constructor_args
    set_zero_level_before_generating_mipmap
    unfold_short_circuit_as_ternary_operation
    unpack_alignment_workaround_with_unpack_buffer
    unpack_image_height_workaround_with_unpack_buffer
    use_intermediary_for_copy_texture_image
    use_unused_standard_shared_blocks
  Traceback (most recent call last):
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/testing/serially_executed_browser_test_case.py", line 206, in <lambda>
      return lambda self: based_method(self, *args)
    File "/b/s/w/ir/content/test/gpu/gpu_tests/gpu_integration_test.py", line 132, in _RunGpuTest
      self.RunActualGpuTest(url, *args)
    File "/b/s/w/ir/content/test/gpu/gpu_tests/webgl_conformance_integration_test.py", line 204, in RunActualGpuTest
      getattr(self, test_name)(test_path, *args[1:])
    File "/b/s/w/ir/content/test/gpu/gpu_tests/webgl_conformance_integration_test.py", line 218, in _RunConformanceTest
      self._CheckTestCompletion()
    File "/b/s/w/ir/content/test/gpu/gpu_tests/webgl_conformance_integration_test.py", line 214, in _CheckTestCompletion
      self.fail(self._WebGLTestMessages(self.tab))
  AssertionError: buffer should match expected values
  FAIL buffer should match expected values
  buffer should match expected values
  FAIL buffer should match expected values
  buffer should match expected values
  FAIL buffer should match expected values
  getError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode
  FAIL getError expected: INVALID_OPERATION. Was NO_ERROR : wrong primitive mode

enne@, could you please take a look and see if it's related to https://chromium-review.googlesource.com/c/chromium/src/+/986744, or know if it's related to other CLs? Thanks!