[wasm-test] WasmModuleBuilder.addCustomSection in the JS builder API.

test/mjsunit/wasm/js-api.js

Index: test/mjsunit/wasm/js-api.js
diff --git a/test/mjsunit/wasm/js-api.js b/test/mjsunit/wasm/js-api.js
index 3c195dc130a3cad7cbd98d91ac4246ced3817ac7..873f4ddff67e309de7cb4ffe19c8ef71413db69e 100644
--- a/test/mjsunit/wasm/js-api.js
+++ b/test/mjsunit/wasm/js-api.js
@@ -292,19 +292,10 @@ assertErrorMessage(
 
 let customSectionModuleBinary2 = (() => {
   let builder = new WasmModuleBuilder();
-  builder.addExplicitSection([kUnknownSectionCode, 3, 1, 'x'.charCodeAt(0), 2]);
-  builder.addExplicitSection([
-    kUnknownSectionCode, 6, 3, 'f'.charCodeAt(0), 'o'.charCodeAt(0),
-    'o'.charCodeAt(0), 66, 77
-  ]);
-  builder.addExplicitSection([
-    kUnknownSectionCode, 7, 3, 'f'.charCodeAt(0), 'o'.charCodeAt(0),
-    'o'.charCodeAt(0), 91, 92, 93
-  ]);
-  builder.addExplicitSection([
-    kUnknownSectionCode, 7, 3, 'f'.charCodeAt(0), 'o'.charCodeAt(0),
-    'x'.charCodeAt(0), 99, 99, 99
-  ]);
+  builder.addCustomSection('x', [2]);
+  builder.addCustomSection('foo', [66, 77]);
+  builder.addCustomSection('foo', [91, 92, 93]);
+  builder.addCustomSection('fox', [99, 99, 99]);
   return new Int8Array(builder.toBuffer());
 })();
 var arr = moduleCustomSections(new Module(customSectionModuleBinary2), 'x');