[wasm][anyref] Add test for the default value of anyfunc locals

The implementation already exists, but the test doesn't.

R=titzer@chromium.org

Bug: v8:7581
Change-Id: I42e1b0a1c930ec4cc1f1701d5613828acab4fc30
Reviewed-on: https://chromium-review.googlesource.com/c/1426123Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59038}

test/mjsunit/wasm/anyfunc.js

@@ -7,7 +7,7 @@
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
-(function testAnyRefIdentityFunction() {
+(function testAnyFuncIdentityFunction() {
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   builder.addFunction('main', kSig_a_a)
@@ -23,7 +23,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
       instance.exports.main, instance.exports.main(instance.exports.main));
 })();
 
-(function testPassAnyRefToImportedFunction() {
+(function testPassAnyFuncToImportedFunction() {
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   const sig_index = builder.addType(kSig_v_a);
@@ -42,7 +42,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   main(main);
 })();
 
-(function testPassAnyRefWithGCWithLocals() {
+(function testPassAnyFuncWithGCWithLocals() {
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   const ref_sig = builder.addType(kSig_v_a);
@@ -78,7 +78,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   main(main);
 })();
 
-(function testPassAnyRefWithGC() {
+(function testPassAnyFuncWithGC() {
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   const ref_sig = builder.addType(kSig_v_a);
@@ -102,7 +102,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   main(main);
 })();
 
-(function testPassAnyRefWithGCInWrapper() {
+(function testPassAnyFuncWithGCInWrapper() {
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   const kSig_a_iai = makeSig([kWasmI32, kWasmAnyFunc, kWasmI32], [kWasmAnyFunc]);
@@ -123,3 +123,16 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const result = main(triggerGCParam, main, triggerGCParam);
   assertSame(main, result);
 })();
+
+(function testAnyFuncDefaultValue() {
+  print(arguments.callee.name);
+  const builder = new WasmModuleBuilder();
+  const sig_index = builder.addType(kSig_a_v);
+  builder.addFunction('main', sig_index)
+      .addLocals({anyfunc_count: 1})
+      .addBody([kExprGetLocal, 0])
+      .exportFunc();
+
+  const main = builder.instantiate().exports.main;
+  assertEquals(null, main());
+})();

test/mjsunit/wasm/wasm-constants.js

@@ -152,6 +152,7 @@ let kSig_v_r = makeSig([kWasmAnyRef], []);
 let kSig_v_a = makeSig([kWasmAnyFunc], []);
 let kSig_v_rr = makeSig([kWasmAnyRef, kWasmAnyRef], []);
 let kSig_r_v = makeSig([], [kWasmAnyRef]);
+let kSig_a_v = makeSig([], [kWasmAnyFunc]);
 
 function makeSig(params, results) {
   return {params: params, results: results};