fix corner case in arguments

fixes #4200

lib/compress.js

@@ -9170,6 +9170,7 @@ merge(Compressor.prototype, {
             var i = 0, p;
             while (p = compressor.parent(i++)) {
                 if (p instanceof AST_Lambda) {
+                    if (p instanceof AST_Accessor) return;
                     fn_parent = compressor.parent(i);
                     return p;
                 }

test/compress/arguments.js

@@ -783,3 +783,27 @@ issue_3420_7: {
     }
     expect_stdout: "true"
 }
+
+issue_4200: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+    }
+    input: {
+        var o = {
+            get p() {
+                return arguments[0];
+            },
+        };
+        console.log(o.p);
+    }
+    expect: {
+        var o = {
+            get p() {
+                return arguments[0];
+            },
+        };
+        console.log(o.p);
+    }
+    expect_stdout: "undefined"
+}