Fix chromatic fringing shader undefined behavior with negative values (#8438)

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>

Author: mvaligursky

src/scene/shader-lib/glsl/chunks/render-pass/frag/compose/compose-fringing.js

@@ -5,7 +5,7 @@ export default /* glsl */`
         vec3 applyFringing(vec3 color, vec2 uv) {
             // offset depends on the direction from the center
             vec2 centerDistance = uv - 0.5;
-            vec2 offset = fringingIntensity * pow(centerDistance, vec2(2.0, 2.0));
+            vec2 offset = fringingIntensity * centerDistance * centerDistance;
 
             color.r = texture2D(sceneTexture, uv - offset).r;
             color.b = texture2D(sceneTexture, uv + offset).b;

src/scene/shader-lib/wgsl/chunks/render-pass/frag/compose/compose-fringing.js

@@ -5,7 +5,7 @@ export default /* wgsl */`
         fn applyFringing(color: vec3f, uv: vec2f) -> vec3f {
             // offset depends on the direction from the center
             let centerDistance = uv - 0.5;
-            let offset = uniform.fringingIntensity * pow(centerDistance, vec2f(2.0));
+            let offset = uniform.fringingIntensity * centerDistance * centerDistance;
 
             var colorOut = color;
             colorOut.r = textureSample(sceneTexture, sceneTextureSampler, uv - offset).r;