Fix generation of f16 values.

The generator script was not using the test values for `f16`, they
always got a zero initialization. This CL fixes the script to generate
`f16` values.

Change-Id: I95e8f2c7007251a646de05b4f7fe0aad14e740f8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/109342
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
diff --git a/test/tint/builtins/gen/var/max/e14f2b.wgsl b/test/tint/builtins/gen/var/max/e14f2b.wgsl
index 12fd3d9..c714541 100644
--- a/test/tint/builtins/gen/var/max/e14f2b.wgsl
+++ b/test/tint/builtins/gen/var/max/e14f2b.wgsl
@@ -25,8 +25,8 @@
 
 // fn max(vec<4, f16>, vec<4, f16>) -> vec<4, f16>
 fn max_e14f2b() {
-  var arg_0 = vec4<f16>(f16());
-  var arg_1 = vec4<f16>(f16());
+  var arg_0 = vec4<f16>(1.h);
+  var arg_1 = vec4<f16>(1.h);
   var res: vec4<f16> = max(arg_0, arg_1);
 }