BREAKING: `DENO_FUTURE=1` by default, or welcome to Deno 2.0 (#25213)

This commit effectively turns Deno into Deno 2.0.

This is done by forcing `DENO_FUTURE=1` env var, that was available in
the past few months to try Deno 2 changes.

This commit contains several breaking changes scheduled for Deno 2:
- all deprecated JavaScript APIs are not available any more, mostly
`Deno.*` APIs
- `window` global is removed
- FFI, WebGPU and FS APIs are now stable and don't require
`--unstable-*` flags
- import assertions are no longer supported
- "bring your own node modules" is enabled by default

This is the first commit in a series that are scheduled before the Deno
2 release.

Follow up work is tracked in
https://github.com/denoland/deno/issues/25241.

---------

Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>
Co-authored-by: Nayeem Rahman <nayeemrmn99@gmail.com>
Co-authored-by: Nathan Whitaker <nathan@deno.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index a0888ca58..e339cb714 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -117,8 +117,8 @@ pub static DENO_DISABLE_PEDANTIC_NODE_WARNINGS: Lazy<bool> = Lazy::new(|| {
     .is_some()
 });
 
-pub static DENO_FUTURE: Lazy<bool> =
-  Lazy::new(|| std::env::var("DENO_FUTURE").ok().is_some());
+// TODO(2.0): remove this in a follow up.
+pub static DENO_FUTURE: Lazy<bool> = Lazy::new(|| true);
 
 pub fn jsr_url() -> &'static Url {
   static JSR_URL: Lazy<Url> = Lazy::new(|| {
@@ -1680,6 +1680,7 @@ impl CliOptions {
         }
       });
 
+    // TODO(2.0): remove this conditional and enable these features in `99_main.js` by default.
     if *DENO_FUTURE {
       let future_features = [
         deno_runtime::deno_ffi::UNSTABLE_FEATURE_NAME.to_string(),