Remove tint's usage of Validator

Also update comments and arch design to remove references to the
Validator.

Bug: tint:642
Change-Id: Ic0b4779ae4712a393ff209014daf25e23f32be6d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/47061
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

src/resolver/decoration_validation_test.cc

@@ -256,7 +256,7 @@ TEST_P(VariableDecorationTest, IsValid) {
   }
 }
 INSTANTIATE_TEST_SUITE_P(
-    ValidatorTest,
+    ResolverDecorationValidationTest,
     VariableDecorationTest,
     testing::Values(TestParams{DecorationKind::kAccess, false},
                     TestParams{DecorationKind::kAlign, false},
@@ -290,7 +290,7 @@ TEST_P(FunctionDecorationTest, IsValid) {
   }
 }
 INSTANTIATE_TEST_SUITE_P(
-    ValidatorTest,
+    ResolverDecorationValidationTest,
     FunctionDecorationTest,
     testing::Values(TestParams{DecorationKind::kAccess, false},
                     TestParams{DecorationKind::kAlign, false},

src/resolver/resolver.cc

@@ -1252,8 +1252,7 @@ bool Resolver::MemberAccessor(ast::MemberAccessorExpression* expr) {
       }
     } else {
       // The vector will have a number of components equal to the length of
-      // the swizzle. This assumes the validator will check that the swizzle
-      // is correct.
+      // the swizzle.
       ret = builder_->create<type::Vector>(vec->type(),
                                            static_cast<uint32_t>(size));
     }