test/tint/builtins: Generate abstract numeric tests

Change-Id: I2da181af0694f73ec4be07ed40e4e70d49b53583
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/97140
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
diff --git a/test/tint/builtins/gen/var/mix/6f8adc.wgsl b/test/tint/builtins/gen/var/mix/6f8adc.wgsl
index c1efe6b..c83a5c7 100644
--- a/test/tint/builtins/gen/var/mix/6f8adc.wgsl
+++ b/test/tint/builtins/gen/var/mix/6f8adc.wgsl
@@ -25,9 +25,9 @@
 
 // fn mix(vec<2, f32>, vec<2, f32>, vec<2, f32>) -> vec<2, f32>
 fn mix_6f8adc() {
-  var arg_0 = vec2<f32>();
-  var arg_1 = vec2<f32>();
-  var arg_2 = vec2<f32>();
+  var arg_0 = vec2<f32>(1.f);
+  var arg_1 = vec2<f32>(1.f);
+  var arg_2 = vec2<f32>(1.f);
   var res: vec2<f32> = mix(arg_0, arg_1, arg_2);
 }