[wasm] Fix ToNumber conversion

test/mjsunit/wasm/ffi.js

 // Copyright 2015 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 --allow-natives-syntax
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 function testCallFFI(func, check) {
@@ skipping 320 matching lines @@
   builder.addImportWithModule('18', '-3', kSig_v_i);
   builder.addImportWithModule('-3', '18', kSig_v_i);
 
   builder.instantiate({
     foo: {0: print},
     0: {0: print, foo: print},
     18: {'-3': print},
     '-3': {18: print}
   });
 })();
+
+(function ImportSymbolAsVoidDoesNotThrow() {
+  var builder = new WasmModuleBuilder();
+  // Return type is void, so there should be no ToNumber conversion.
+  var index = builder.addImport("func", kSig_v_v);
+  builder.addFunction("main", kSig_v_v)
+      .addBody([kExprCallFunction, 0])
+      .exportFunc();
+  var func = () => Symbol();
+  var main = builder.instantiate({func: func}).exports.main;
+  main();
+})();
+
+(function ToNumberCalledOnImport() {
+  var builder = new WasmModuleBuilder();
+  // Return type is int, so there should be a ToNumber conversion.
+  var index = builder.addImport("func", kSig_i_v);
+  builder.addFunction("main", kSig_i_v)
+      .addBody([kExprCallFunction, 0])
+      .exportFunc();
+  var num_valueOf = 0;
+  function Foo() {}
+  Foo.prototype.valueOf = () => ++num_valueOf;
+  var func = () => new Foo();
+  var main = builder.instantiate({func: func}).exports.main;
+  main();
+  assertEquals(1, num_valueOf);
+  main();
+  assertEquals(2, num_valueOf);
+})();
+
+(function ToNumberNotCalledOnVoidImport() {
+  var builder = new WasmModuleBuilder();
+  // Return type is void, so there should be no ToNumber conversion.
+  var index = builder.addImport("func", kSig_v_v);
+  builder.addFunction("main", kSig_v_v)
+      .addBody([kExprCallFunction, 0])
+      .exportFunc();
+  var num_valueOf = 0;
+  function Foo() {}
+  Foo.prototype.valueOf = () => ++num_valueOf;
+  var func = () => new Foo();
+  var main = builder.instantiate({func: func}).exports.main;
+  main();
+  main();
+  assertEquals(0, num_valueOf);
+})();