Suppress two GLES2 conformance failures on Mac NVIDIA.

BUG=630452
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
R=zmo@chromium.org
TBR=piman@chromium.org
NOTRY=true

Review-Url: https://codereview.chromium.org/2170153002
Cr-Commit-Position: refs/heads/master@{#406997}

gpu/gles2_conform_support/gles2_conform_test_expectations.txt

@@ -76,6 +76,9 @@
 253674 MAC : GL2Tests_glUniform_input_run = FAIL
 253674 MAC : GL2Tests_three_uniforms_input_run = FAIL
 
+630452 MAC NVIDIA : GL2FixedTests_color_ramp_input_run = SKIP
+630452 MAC NVIDIA : GL2FixedTests_buffer_color_input_run = SKIP
+
 393677 CHROMEOS INTEL 0xa011 : GL_acos_input_run = FAIL
 393677 CHROMEOS INTEL 0xa011 : GL_asin_input_run = FAIL
 393677 CHROMEOS INTEL 0xa011 : GL_atan_input_run = FAIL