Prevent old browsers from reaching code they don't understand.
Prevent old browsers from reaching code they don't understand.

CortesHub/glsl-sandbox,RobertoMalatesta/glsl-sandbox,mrdoob/glsl-sandbox,mrdoob/glsl-sandbox,RobertoMalatesta/glsl-sandbox,beni55/glsl-sandbox,mrdoob/glsl-sandbox,CortesHub/glsl-sandbox,QingchaoHu/glsl-sandbox,oresmus/glsl-sandbox,RobertoMalatesta/glsl-sandbox,mrdoob/glsl-sandbox,CortesHub/glsl-sandbox,QingchaoHu/glsl-sandbox,beni55/glsl-sandbox,QingchaoHu/glsl-sandbox,oresmus/glsl-sandbox,oresmus/glsl-sandbox,beni55/glsl-sandbox