fuzz(mutate): enable the custom-page-sizes proposal as necessary (#1619)

* fuzz(mutate): enable the custom-page-sizes proposal as necessary

If `wasm-smith` enabled it, then we need to enable it for validation of the
mutated binaries.

* Enable all validator features

* fix unused var

fuzz/src/mutate.rs

@@ -11,7 +11,7 @@ pub fn run(u: &mut Unstructured<'_>) -> Result<()> {
 
     let mut seed = 0;
     let mut preserve_semantics = false;
-    let (wasm, config) = crate::generate_valid_module(u, |config, u| {
+    let (wasm, _config) = crate::generate_valid_module(u, |config, u| {
         config.exceptions_enabled = false;
         config.gc_enabled = false;
         seed = u.arbitrary()?;
@@ -55,19 +55,7 @@ pub fn run(u: &mut Unstructured<'_>) -> Result<()> {
         }
     };
 
-    // Note that on-by-default features in wasmparser are not disabled here if
-    // the feature was disabled in `config` when the module was generated. For
-    // example if the input module doesn't have simd then wasm-mutate may
-    // produce a module that uses simd, which is ok and expected.
-    //
-    // Otherwise only forward some off-by-default features which are affected by
-    // wasm-smith's generation of modules and wasm-mutate otherwise won't add
-    // itself if it doesn't already exist.
-    let mut features = WasmFeatures::default();
-    features.set(WasmFeatures::RELAXED_SIMD, config.relaxed_simd_enabled);
-    features.set(WasmFeatures::MULTI_MEMORY, config.max_memories > 1);
-    features.set(WasmFeatures::MEMORY64, config.memory64_enabled);
-    features.set(WasmFeatures::THREADS, config.threads_enabled);
+    let features = WasmFeatures::all();
 
     for (i, mutated_wasm) in iterator.take(10).enumerate() {
         let mutated_wasm = match mutated_wasm {