Add support for all blendmodes if we have GL_KHR_blend_equation_advanced.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 0b8d68d80f362255cdd347cf5335a116dd0ed0b9..01d20c7f1ae22eee9befd13b556137b244c59028 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2742,6 +2742,10 @@ Capabilities GLES2DecoderImpl::GetCapabilities() {
   caps.image = true;
 
   caps.blend_minmax = feature_info_->feature_flags().ext_blend_minmax;
+  caps.blend_equation_advanced =
+      feature_info_->feature_flags().blend_equation_advanced;
+  caps.blend_equation_advanced_coherent =
+      feature_info_->feature_flags().blend_equation_advanced_coherent;
   return caps;
 }