tint/writer/hlsl: Inline constant expressions

This is required to handle materialized values, and for constant
expressions.

Bug: tint:1504
Change-Id: I79ad567954de2d1cfea09dda255894e4e2aa678e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/92081
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
diff --git a/test/tint/builtins/textureLoad/texture_external_param.wgsl.expected.hlsl b/test/tint/builtins/textureLoad/texture_external_param.wgsl.expected.hlsl
index 2fb9dfe..b933cd1 100644
--- a/test/tint/builtins/textureLoad/texture_external_param.wgsl.expected.hlsl
+++ b/test/tint/builtins/textureLoad/texture_external_param.wgsl.expected.hlsl
@@ -80,7 +80,7 @@
 }
 
 void doTextureLoad() {
-  float4 res = textureLoad2d(arg_0, ext_tex_plane_1, tint_symbol_2(ext_tex_params, 0u), int2(0, 0));
+  float4 res = textureLoad2d(arg_0, ext_tex_plane_1, tint_symbol_2(ext_tex_params, 0u), (0).xx);
 }
 
 struct tint_symbol_1 {
@@ -89,7 +89,7 @@
 
 float4 vertex_main_inner() {
   doTextureLoad();
-  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+  return (0.0f).xxxx;
 }
 
 tint_symbol_1 vertex_main() {