fix(tests): remove (now)unecessary feature flags

tests/fixtures/bad-cargo-toml/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(use_extern_macros, wasm_import_module)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;
 

tests/fixtures/js-hello-world/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(use_extern_macros, wasm_import_module)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;
 

tests/fixtures/no-compile/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(use_extern_macros, wasm_import_module)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;
 

tests/fixtures/no-readme/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(use_extern_macros, wasm_import_module)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;
 

tests/fixtures/scopes/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(use_extern_macros, wasm_import_module)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;
 

tests/fixtures/serde-feature/src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(proc_macro, wasm_import_module, wasm_custom_section)]
+#![feature(use_extern_macros)]
 
 extern crate wasm_bindgen;