core: don't include_str extension js code (#10786)

This speeds up incremental rebuild when only touching JS files by 13-15%

Rebuild time after `touch 01_broadcast_channel.js`:

main: run 1 49.18s, run 2 50.34s
this: run 1 43.12s, run 2 43.19s

1 files changed, 6 insertions, 4 deletions

diff --git a/extensions/timers/benches/timers_ops.rs b/extensions/timers/benches/timers_ops.rs
index 18ef10336..e31fe31ac 100644
--- a/extensions/timers/benches/timers_ops.rs
+++ b/extensions/timers/benches/timers_ops.rs
@@ -9,10 +9,12 @@ fn setup() -> Vec<Extension> {
     deno_timers::init::<deno_timers::NoTimersPermission>(),
     Extension::builder()
     .js(vec![
-      ("setup", r#"
-      const { opNow, setTimeout, handleTimerMacrotask } = globalThis.__bootstrap.timers;
-      Deno.core.setMacrotaskCallback(handleTimerMacrotask);
-      "#),
+      ("setup",
+        Box::new(|| Ok(r#"
+        const { opNow, setTimeout, handleTimerMacrotask } = globalThis.__bootstrap.timers;
+        Deno.core.setMacrotaskCallback(handleTimerMacrotask);
+        "#.to_owned())),
+      ),
     ])
     .state(|state| {
       state.put(deno_timers::NoTimersPermission{});