Revert "Use Fused-Multiply-Add (#232)" (#241)

This reverts commit bd2de37.

Author: parasyte

examples/custom-shader/shaders/noise.wgsl

@@ -10,7 +10,7 @@ fn vs_main(
     [[location(0)]] position: vec2<f32>,
 ) -> VertexOutput {
     var out: VertexOutput;
-    out.tex_coord = fma(position, vec2<f32>(0.5, -0.5), vec2<f32>(0.5, 0.5));
+    out.tex_coord = position * vec2<f32>(0.5, -0.5) + 0.5;
     out.position = vec4<f32>(position, 0.0, 1.0);
     return out;
 }

shaders/scale.wgsl

@@ -15,7 +15,7 @@ fn vs_main(
     [[location(0)]] position: vec2<f32>,
 ) -> VertexOutput {
     var out: VertexOutput;
-    out.tex_coord = fma(position, vec2<f32>(0.5, -0.5), vec2<f32>(0.5, 0.5));
+    out.tex_coord = position * vec2<f32>(0.5, -0.5) + 0.5;
     out.position = r_locals.transform * vec4<f32>(position, 0.0, 1.0);
     return out;
 }