More WGSL flat issues (#3935)

Fix a few more tests that should no longer fail in compat
as errors have been moved from shader creation time to
pipeline creation time.

src/webgpu/shader/validation/shader_io/interpolate.spec.ts

@@ -133,9 +133,7 @@ g.test('integral_types')
       use_struct: t.params.use_struct,
     });
 
-    const expectSuccess = t.isCompatibility
-      ? t.params.attribute === '@interpolate(flat, either)'
-      : t.params.attribute.startsWith('@interpolate(flat');
+    const expectSuccess = t.params.attribute.startsWith('@interpolate(flat');
     t.expectCompileResult(expectSuccess, code);
   });
 
@@ -153,7 +151,7 @@ g.test('duplicate')
     t.expectCompileResult(t.params.attr === '', code);
   });
 
-const kValidationTests: { [key: string]: { src: string; pass: boolean; compatPass?: boolean } } = {
+const kValidationTests: { [key: string]: { src: string; pass: boolean } } = {
   valid: {
     src: `@interpolate(perspective)`,
     pass: true,
@@ -165,7 +163,6 @@ const kValidationTests: { [key: string]: { src: string; pass: boolean; compatPas
   trailing_comma_one_arg: {
     src: `@interpolate(flat,)`,
     pass: true,
-    compatPass: false,
   },
   trailing_comma_two_arg: {
     src: `@interpolate(perspective, center,)`,
@@ -223,9 +220,6 @@ g.test('interpolation_validation')
     @builtin(position) vec4<f32> {
   return vec4f(0);
 }`;
-    const expectSuccess =
-      kValidationTests[t.params.attr].pass &&
-      (t.isCompatibility ? kValidationTests[t.params.attr].compatPass ?? true : true);
-
+    const expectSuccess = kValidationTests[t.params.attr].pass;
     t.expectCompileResult(expectSuccess, code);
   });