Do not deoptimize entire super class when adding a property (#4489)

src/ast/nodes/shared/ObjectEntity.ts

@@ -128,7 +128,7 @@ export class ObjectEntity extends ExpressionEntity {
 			: this.allProperties) {
 			property.deoptimizePath(subPath);
 		}
-		this.prototypeExpression?.deoptimizePath(path.length === 1 ? [UnknownKey, UnknownKey] : path);
+		this.prototypeExpression?.deoptimizePath(path.length === 1 ? [...path, UnknownKey] : path);
 	}
 
 	deoptimizeThisOnEventAtPath(

test/form/samples/deoptimize-superclass/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'does not deoptimize the entire superclass when reassigning a property'
+};

test/form/samples/deoptimize-superclass/_expected.js

@@ -0,0 +1,2 @@
+// Everything else should be removed
+console.log('retained');

test/form/samples/deoptimize-superclass/main.js

@@ -0,0 +1,10 @@
+class Foo {}
+
+Foo.prototype.bar = {};
+
+class Bar extends Foo {}
+
+Bar.baz = {};
+
+// Everything else should be removed
+console.log('retained');