Add mising computeboids casts.

This CL adds in missing casts from i32 to f32 when using the count
variables in computeboids to create vec3<f32> values.

Change-Id: I3e66e2db0fc626b94ae98142cd95a65feff7fc53
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/20627
Reviewed-by: David Neto <dneto@google.com>
diff --git a/test/compute_boids.wgsl b/test/compute_boids.wgsl
index d6d8058..4f2f44f 100644
--- a/test/compute_boids.wgsl
+++ b/test/compute_boids.wgsl
@@ -113,10 +113,11 @@
     }
   }
   if (cMassCount > 0) {
-    cMass = (cMass / vec2<f32>(cMassCount, cMassCount)) + vPos;
+    cMass =
+      (cMass / vec2<f32>(cast<f32>(cMassCount), cast<f32>(cMassCount))) + vPos;
   }
   if (cVelCount > 0) {
-    cVel = cVel / vec2<f32>(cVelCount, cVelCount);
+    cVel = cVel / vec2<f32>(cast<f32>(cVelCount), cast<f32>(cVelCount));
   }
 
   vVel = vVel + (cMass * params.rule1Scale) + (colVel * params.rule2Scale) +