fix corner cases in properties (#5178)

fixes #5177

test/compress/awaits.js

@@ -453,7 +453,7 @@ object_function: {
         }).f();
     }
     expect: {
-        (async function() {
+        (async () => {
             console.log("PASS");
         })();
     }
@@ -2212,3 +2212,29 @@ issue_5159_2: {
     ]
     node_version: ">=8"
 }
+
+issue_5177: {
+    options = {
+        properties: true,
+    }
+    input: {
+        (async function() {
+            return {
+                p(await) {},
+            }.p;
+        })().then(function(a) {
+            console.log(typeof a);
+        });
+    }
+    expect: {
+        (async function() {
+            return {
+                p(await) {},
+            }.p;
+        })().then(function(a) {
+            console.log(typeof a);
+        });
+    }
+    expect_stdout: "function"
+    node_version: ">=8"
+}