Remove unnecessary MSAA on MRT

src/babylon.engine.ts

@@ -2827,12 +2827,7 @@
 
             var colorRenderbuffer = gl.createRenderbuffer();
             gl.bindRenderbuffer(gl.RENDERBUFFER, colorRenderbuffer);
-            gl.renderbufferStorageMultisample(gl.RENDERBUFFER, 4, gl.RGBA8, width, height);
             gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
-            gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, colorRenderbuffer);
-            gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT1, gl.RENDERBUFFER, colorRenderbuffer);
-            gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, colorRenderbuffer);
-
             var width = size.width || size;
             var height = size.height || size;