Add explanatory comments for ReactIs import

Co-authored-by: Archmonger <16909269+Archmonger@users.noreply.github.com>

Author: Copilot

tests/test_reactjs/js_fixtures/subcomponent-notation.js

@@ -1,5 +1,7 @@
 import React from "https://esm.sh/v135/react@19.0"
 import ReactDOM from "https://esm.sh/v135/react-dom@19.0/client"
+// Explicitly import react-is to ensure it's loaded before react-bootstrap
+// This prevents race conditions where react-bootstrap tries to use React context before deps are ready
 import * as ReactIs from "https://esm.sh/v135/react-is@19.0"
 import {InputGroup, Form} from "https://esm.sh/v135/react-bootstrap@2.10.2?deps=react@19.0,react-dom@19.0,react-is@19.0&exports=InputGroup,Form";
 export {InputGroup, Form};

tests/test_web/js_fixtures/subcomponent-notation.js

@@ -1,5 +1,7 @@
 import React from "https://esm.sh/v135/react@19.0"
 import ReactDOM from "https://esm.sh/v135/react-dom@19.0/client"
+// Explicitly import react-is to ensure it's loaded before react-bootstrap
+// This prevents race conditions where react-bootstrap tries to use React context before deps are ready
 import * as ReactIs from "https://esm.sh/v135/react-is@19.0"
 import {InputGroup, Form} from "https://esm.sh/v135/react-bootstrap@2.10.2?deps=react@19.0,react-dom@19.0,react-is@19.0&exports=InputGroup,Form";
 export {InputGroup, Form};