[wasm] Start function must not have a return value.

test/mjsunit/wasm/start-function.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --expose-wasm
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 function instantiate(sig, body) {
   var builder = new WasmModuleBuilder();
 
   var func = builder.addFunction("", sig)
     .addBody(body);
 
   builder.addStart(func.index);
 
   return builder.instantiate();
 }
 
-function assertFails(sig, body) {
-  try {
-    var module = instantiate(sig, body);
-    print("expected failure, but passes");
-    assertFalse(true);
-  } catch (expected) {
-    print("ok: " + expected);
-  }
-}
-
 function assertVerifies(sig, body) {
   var module = instantiate(sig, body);
   assertFalse(module === undefined);
   assertFalse(module === null);
   assertFalse(module === 0);
   assertEquals("object", typeof module);
   return module;
 }
 
 assertVerifies(kSig_v_v, [kExprNop]);
-assertVerifies(kSig_i_v, [kExprI8Const, 0]);
 
 // Arguments aren't allow to start functions.
-assertFails(kSig_i_i, [kExprGetLocal, 0]);
-assertFails(kSig_i_ii, [kExprGetLocal, 0]);
-assertFails(kSig_i_dd, [kExprGetLocal, 0]);
+assertThrows(() => {instantiate(kSig_i_i, [kExprGetLocal, 0]);});
+assertThrows(() => {instantiate(kSig_i_ii, [kExprGetLocal, 0]);});
+assertThrows(() => {instantiate(kSig_i_dd, [kExprGetLocal, 0]);});
+assertThrows(() => {instantiate(kSig_i_v, [kExprI8Const, 0]);});
 
 (function testInvalidIndex() {
   print("testInvalidIndex");
   var builder = new WasmModuleBuilder();
 
   var func = builder.addFunction("", kSig_v_v)
     .addBody([kExprNop]);
 
   builder.addStart(func.index + 1);
 
@@ skipping 45 matching lines @@
 
   builder.addImport("foo", sig_index);
   var func = builder.addFunction("", sig_index)
     .addBody([kExprCallFunction, 0]);
 
   builder.addStart(func.index);
 
   var module = builder.instantiate(ffi);
   assertTrue(ranned);
 })();