[wasm] Fix string conversion of customSections name

R=titzer@chromium.org

Bug: v8:5815
Change-Id: Ied267a431ed294f022628169e811069f2a4851b1
Reviewed-on: https://chromium-review.googlesource.com/599875
Commit-Queue: Andreas Rossberg <rossberg@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47133}

src/wasm/wasm-js.cc

@@ -235,17 +235,10 @@ void WebAssemblyModuleCustomSections(
   auto maybe_module = GetFirstArgumentAsModule(args, &thrower);
   if (thrower.error()) return;
 
-  if (args.Length() < 2) {
-    thrower.TypeError("Argument 1 must be a string");
-    return;
-  }
-
-  i::Handle<i::Object> name = Utils::OpenHandle(*args[1]);
-  if (!name->IsString()) {
-    thrower.TypeError("Argument 1 must be a string");
-    return;
-  }
-
+  i::MaybeHandle<i::Object> maybe_name =
+      i::Object::ToString(i_isolate, Utils::OpenHandle(*args[1]));
+  i::Handle<i::Object> name;
+  if (!maybe_name.ToHandle(&name)) return;
   auto custom_sections =
       i::wasm::GetCustomSections(i_isolate, maybe_module.ToHandleChecked(),
                                  i::Handle<i::String>::cast(name), &thrower);

test/mjsunit/wasm/js-api.js

@@ -307,12 +307,6 @@ assertEq(arr.length, 0);
 assertErrorMessage(
     () => moduleCustomSections(1), TypeError,
     'first argument must be a WebAssembly.Module');
-assertErrorMessage(
-    () => moduleCustomSections(emptyModule), TypeError,
-    'second argument must be a String');
-assertErrorMessage(
-    () => moduleCustomSections(emptyModule, 3), TypeError,
-    'second argument must be a String');
 
 let customSectionModuleBinary2 = (() => {
   let builder = new WasmModuleBuilder();
@@ -334,6 +328,15 @@ assertArrayBuffer(arr[1], [91, 92, 93]);
 var arr = moduleCustomSections(new Module(customSectionModuleBinary2), 'bar');
 assertEq(arr instanceof Array, true);
 assertEq(arr.length, 0);
+var o = {toString() { return "foo" }}
+var arr = moduleCustomSections(new Module(customSectionModuleBinary2), o);
+assertEq(arr instanceof Array, true);
+assertEq(arr.length, 2);
+assertArrayBuffer(arr[0], [66, 77]);
+assertArrayBuffer(arr[1], [91, 92, 93]);
+var o = {toString() { throw "boo!" }}
+assertThrows(
+  () => moduleCustomSections(new Module(customSectionModuleBinary2), o));
 
 // 'WebAssembly.Instance' data property
 let instanceDesc = Object.getOwnPropertyDescriptor(WebAssembly, 'Instance');

test/mjsunit/wasm/jsapi-harness.js

@@ -8,8 +8,6 @@
 // Flags: --expose-wasm --allow-natives-syntax
 
 const known_failures = {
-  "'WebAssembly.Module.customSections' method":
-    'https://bugs.chromium.org/p/v8/issues/detail?id=5815',
   "'WebAssembly.Table.prototype.get' method":
     'https://bugs.chromium.org/p/v8/issues/detail?id=5507',
   "'WebAssembly.Table.prototype.set' method":