#3277 Remove shader file which is exceeeding

src/Shaders/highlightLayerThreshold.fragment.fx

@@ -1,13 +0,0 @@
-precision highp float;
-
-varying vec2 vUV;
-
-uniform float threshold;
-uniform sampler2D textureSampler;
-
-void main(void) {
-    vec4 color = texture2D(textureSampler, vUV);
-    float alpha = smoothstep(.0, threshold, color.a);
-    color.a = alpha;
-    gl_FragColor = color * alpha;
-}