Fetch polyfill

LICENSING.md

@@ -11,6 +11,7 @@ The following files are licensed under MIT:
 
 ```
 src/http/Client.zig
+src/polyfill/fetch.js
 ```
 
 The following directories and their subdirectories are licensed under their

src/browser/browser.zig

@@ -42,6 +42,8 @@ const FetchResult = @import("../http/Client.zig").Client.FetchResult;
 const UserContext = @import("../user_context.zig").UserContext;
 const HttpClient = @import("asyncio").Client;
 
+const polyfill = @import("../polyfill/polyfill.zig");
+
 const log = std.log.scoped(.browser);
 
 // Browser is an instance of the browser.
@@ -355,6 +357,9 @@ pub const Page = struct {
         log.debug("start js env", .{});
         try self.session.env.start();
 
+        // load polyfills
+        try polyfill.load(alloc, self.session.env);
+
         // inspector
         if (self.session.inspector) |inspector| {
             inspector.contextCreated(self.session.env, "", self.origin.?, auxData);