fixed missing errors on assignment pattern in object expression (#10607)

* 🐛 fixed missing errors on assignment pattern in object expression

* ♻️ remove a non-needed comment

* 🐛 missed adding comma in the test input

* 🐛 fixed the failing valid-property-initializer test

packages/babel-parser/src/parser/expression.js

@@ -204,7 +204,10 @@ export default class ExpressionParser extends LValParser {
       node.left = this.match(tt.eq)
         ? this.toAssignable(left, undefined, "assignment expression")
         : left;
-      refShorthandDefaultPos.start = 0; // reset because shorthand default was used correctly
+
+      if (refShorthandDefaultPos.start >= node.left.start) {
+        refShorthandDefaultPos.start = 0; // reset because shorthand default was used correctly
+      }
 
       this.checkLVal(left, undefined, undefined, "assignment expression");