Use env var V8_BINARY instead of cargo feature

Cargo.toml

@@ -47,11 +47,6 @@ exclude = [
  "!v8/tools/testrunner/utils/dump_build_config.py",
 ]
 
-[features]
-# Enable this feature to download and prebuilt V8 binaries from
-# https://github.com/denoland/rusty_v8/releases
-binary = []
-
 [dependencies]
 lazy_static = "1.4.0"
 libc = "0.2.67"

README.md

@@ -62,13 +62,14 @@ V8 is very large and take a long time to compile. Many users may prefer to use
 a prebuilt version of V8. We publish static libs for every version of rusty v8
 on [Github](https://github.com/denoland/rusty_v8/releases).
 
-To use these prebuilt binaries use the `binary` feature:
+To use these prebuilt binaries use the `V8_BINARY=1` environmental variable:
 
 ```
-cargo build --features="binary"
+V8_BINARY=1 cargo build
 ```
 
-This will cause rusty v8 to download the binaries during the build process.
+This will cause rusty v8 to download the static lib binary during the build
+process.
 
 ## FAQ
 

build.rs

@@ -23,7 +23,7 @@ fn main() {
     .map(|s| s.starts_with("rls"))
     .unwrap_or(false);
 
-  if cfg!(feature = "binary") {
+  if env::var_os("V8_BINARY").is_some() {
     download_static_lib_binaries();
   } else if !(is_trybuild || is_cargo_doc | is_rls) {
     build_v8()