Ensure test fails when feature is off

Differential Revision: https://phabricator.services.mozilla.com/D124601

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1729029
gecko-commit: 3f2f788cc2707a587de408459a77218c7218a782
gecko-reviewers: lth
diff --git a/wasm/jsapi/function/constructor.tentative.any.js b/wasm/jsapi/function/constructor.tentative.any.js
index 3b98996..7ab77c2 100644
--- a/wasm/jsapi/function/constructor.tentative.any.js
+++ b/wasm/jsapi/function/constructor.tentative.any.js
@@ -6,30 +6,37 @@
 }
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     var fun = new WebAssembly.Function({parameters: ["i32", "i32"], results: ["i32"]}, addxy);
     assert_true(fun instanceof WebAssembly.Function)
 }, "construct with JS function")
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({parameters: []}, addxy))
 }, "fail with missing results")
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({results: []}, addxy))
 }, "fail with missing parameters")
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({parameters: [1], results: [true]}, addxy))
 }, "fail with non-string parameters & results")
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({parameters: ["invalid"], results: ["invalid"]}, addxy))
 }, "fail with non-existent parameter and result type")
 
 test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({parameters: [], results: []}, 72))
 }, "fail with non-function object")
 
-test(()  => {
+test(() => {
+    assert_implements(WebAssembly.Function, "WebAssembly.Function is not implemented");
     assert_throws_js(TypeError, () => new WebAssembly.Function({parameters: [], results: []}, {}))
 }, "fail to construct with non-callable object")