Strengthen fast call API test (denoland#1093)

Check that it actually performs the expected operation (adding two
numbers) because it didn't - the callback's function prototype was
wrong. V8 always passes the receiver object as the first parameter.

tests/test_api.rs

@@ -7595,15 +7595,16 @@ fn host_create_shadow_realm_context_callback() {
 #[test]
 fn test_fast_calls() {
  static mut WHO: &str = "none";
- fn fast_fn(a: u32, b: u32) -> u32 {
+ fn fast_fn(_recv: v8::Local<v8::Object>, a: u32, b: u32) -> u32 {
  unsafe { WHO = "fast" };
  a + b
  }
 
  pub struct FastTest;
  impl fast_api::FastFunction for FastTest {
  fn args(&self) -> &'static [fast_api::Type] {
- &[fast_api::Type::Uint32, fast_api::Type::Uint32]
+ use fast_api::Type::*;
+ &[V8Value, Uint32, Uint32]
  }
 
  fn return_type(&self) -> fast_api::CType {
@@ -7617,11 +7618,13 @@ fn test_fast_calls() {
 
  fn slow_fn(
  scope: &mut v8::HandleScope,
- _: v8::FunctionCallbackArguments,
+ args: v8::FunctionCallbackArguments,
  mut rv: v8::ReturnValue,
  ) {
  unsafe { WHO = "slow" };
- rv.set(v8::Boolean::new(scope, false).into());
+ let a = args.get(0).uint32_value(scope).unwrap();
+ let b = args.get(1).uint32_value(scope).unwrap();
+ rv.set_uint32(a + b);
  }
 
  let _setup_guard = setup();
@@ -7639,16 +7642,16 @@ fn test_fast_calls() {
  let value = template.get_function(scope).unwrap();
  global.set(scope, name.into(), value.into()).unwrap();
  let source = r#"
- function f(x, y) { return func(x, y); }
- %PrepareFunctionForOptimization(f);
- f(1, 2);
-"#;
+  function f(x, y) { return func(x, y); }
+  %PrepareFunctionForOptimization(f);
+  if (42 !== f(19, 23)) throw "unexpected";
+ "#;
  eval(scope, source).unwrap();
  assert_eq!("slow", unsafe { WHO });
 
  let source = r#"
  %OptimizeFunctionOnNextCall(f);
- f(1, 2);
+ if (42 !== f(19, 23)) throw "unexpected";
  "#;
  eval(scope, source).unwrap();
  assert_eq!("fast", unsafe { WHO });