In GLES3 spec, there are some behaviors which will lead to undefined behaviors for underlying GPU driver. However, the undefined behavior should be defined clearly in WebGL 2, for example, generate an INVALID_OPERATION error.

Most of these undefined behaviors have been listed in WebGL2 spec in the section 5 <Differences between WebGL and OpenGL ES 3.0> at https://www.khronos.org/registry/webgl/specs/latest/2.0/#5, and we have handled those behaviors correctly in Chromium. 

However, it is reasonable to check all these undefined behaviors one by one before WebGL 2.0 shipment, in order to make sure all of them are handled correctly in Chromium.