Removing a D3D limitation from SwiftShader

The limitation of not being able to have
different values for stencil and stencilBack
was put in place in Angle because of a D3D
limitation, which we do not have in Swift
Shader, so I doubt we need the same limitation.

FYI, this fixes about 600 dEQP tests.

Change-Id: I74d1786c612e817fb5ef46f233751e6f2581c33f
Reviewed-on: https://swiftshader-review.googlesource.com/3321
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
diff --git a/src/OpenGL/libGLESv2/Context.cpp b/src/OpenGL/libGLESv2/Context.cpp
index 8e7ebf9..f658447 100644
--- a/src/OpenGL/libGLESv2/Context.cpp
+++ b/src/OpenGL/libGLESv2/Context.cpp
@@ -2674,14 +2674,6 @@
 			device->setStencilEnable(true);

 			device->setTwoSidedStencil(true);

 

-            if(mState.stencilWritemask != mState.stencilBackWritemask || 

-               mState.stencilRef != mState.stencilBackRef || 

-               mState.stencilMask != mState.stencilBackMask)

-            {

-				ERR("Separate front/back stencil writemasks, reference values, or stencil mask values are invalid under WebGL.");

-                return error(GL_INVALID_OPERATION);

-            }

-

             // get the maximum size of the stencil ref

             Renderbuffer *stencilbuffer = framebuffer->getStencilbuffer();

             GLuint maxStencil = (1 << stencilbuffer->getStencilSize()) - 1;