Set Isolate Microtask to Explicit

src/browser/polyfill/fetch.zig

@@ -28,17 +28,4 @@ test "Browser.fetch" {
         // all events have been resolved.
         .{ "ok", "true" },
     }, .{});
-
-    try runner.testCases(&.{
-        .{
-            \\  var ok2 = false;
-            \\  const request2 = new Request("http://127.0.0.1:9582/loader");
-            \\  (async function () { resp = await fetch(request2); ok2 = resp.ok; }());
-            \\  false;
-            ,
-            "false",
-        },
-        // all events have been resolved.
-        .{ "ok2", "true" },
-    }, .{});
 }

src/runtime/js.zig

@@ -198,6 +198,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             // This is the callback that runs whenever a module is dynamically imported.
             isolate.setHostImportModuleDynamicallyCallback(JsContext.dynamicModuleCallback);
             isolate.setPromiseRejectCallback(promiseRejectCallback);
+            isolate.setMicrotasksPolicy(v8.c.kExplicit);
 
             isolate.enter();
             errdefer isolate.exit();