fix: don’t add function name when operator is not = (#11361)

packages/babel-helper-function-name/src/index.js

@@ -179,7 +179,7 @@ export default function({ node, parent, scope, id }, localBinding = false) {
         return;
       }
     }
-  } else if (t.isAssignmentExpression(parent)) {
+  } else if (t.isAssignmentExpression(parent, { operator: "=" })) {
     // foo = function () {};
     id = parent.left;
   } else if (!id) {

packages/babel-plugin-transform-function-name/test/fixtures/function-name/function-assignment/input.js

@@ -11,3 +11,5 @@ baz = 12;
 bar = function() {
   bar();
 };
+
+qux += function() {}

packages/babel-plugin-transform-function-name/test/fixtures/function-name/function-assignment/output.js

@@ -23,3 +23,5 @@ bar = function (_bar) {
 }(function () {
   bar();
 });
+
+qux += function () {};