Bug 252299

The following test: ``` //@ runWebAssemblySuite("--useWebAssemblyTypedFunctionReferences=true", "--useWebAssemblyGC=true") import * as assert from "../assert.js"; import { compile, instantiate } from "./wast-wrapper.js"; function module(bytes, valid = true) { let buffer = new ArrayBuffer(bytes.length); let view = new Uint8Array(buffer); for (let i = 0; i < bytes.length; ++i) { print(bytes.charCodeAt(i)); view[i] = bytes.charCodeAt(i); } return new WebAssembly.Module(buffer); } function arrayGetUninitializedLocal() { let m = instantiate(`(module (type $a (array (mut i32))) (type $s (struct (field $x (mut i32)) (field $y (mut i64)))) (func (export "arrayGetNull") (local (ref null $a)) (drop (array.get $a (local.get 0) (i32.const 0))) ))`); assert.throws(() => m.exports.arrayGetNull(), WebAssembly.RuntimeError, "array.get to a null reference"); } arrayGetUninitializedLocal(); ``` causes a segfault. This is because of the `LLIntGenerator::addLocal()` method, which only initializes funcref-typed and extern-ref typed locals to the JS null value; not those with struct or array types. It should handle all ref types in the same way.