Add storage texture loads to uniformity tests (#3327)

Loads from a read-write storage texture are considered non-uniform,
whereas loads from a read-only storage texture are uniform.

src/webgpu/shader/validation/uniformity/uniformity.spec.ts

@@ -44,6 +44,8 @@ const kConditions = [
   { cond: 'nonuniform_and2', expectation: false },
   { cond: 'uniform_func_var', expectation: true },
   { cond: 'nonuniform_func_var', expectation: false },
+  { cond: 'storage_texture_ro', expectation: true },
+  { cond: 'storage_texture_rw', expectation: false },
 ];
 
 function generateCondition(condition: string): string {
@@ -99,6 +101,12 @@ function generateCondition(condition: string): string {
     case 'nonuniform_func_var': {
       return `n_f == 0`;
     }
+    case 'storage_texture_ro': {
+      return `textureLoad(ro_storage_texture, vec2()).x == 0`;
+    }
+    case 'storage_texture_rw': {
+      return `textureLoad(rw_storage_texture, vec2()).x == 0`;
+    }
     default: {
       unreachable(`Unhandled condition`);
     }
@@ -189,7 +197,7 @@ g.test('basics')
       .beginSubcases()
   )
   .fn(t => {
-    if (t.params.op === 'textureBarrier') {
+    if (t.params.op === 'textureBarrier' || t.params.cond.startsWith('storage_texture')) {
       t.skipIfLanguageFeatureNotSupported('readonly_and_readwrite_storage_textures');
     }
 
@@ -203,6 +211,9 @@ g.test('basics')
  @group(1) @binding(1) var<storage, read_write> rw_buffer : array<f32, 4>;
  @group(1) @binding(2) var<uniform> uniform_buffer : vec4<f32>;
 
+ @group(2) @binding(0) var ro_storage_texture : texture_storage_2d<rgba8unorm, read>;
+ @group(2) @binding(1) var rw_storage_texture : texture_storage_2d<rgba8unorm, read_write>;
+
  var<private> priv_var : array<f32, 4> = array(0,0,0,0);
 
  const c = false;