Make the esm-eval-returns-exports option be stable and usable in sandbox mode.

(cherry picked from commit e70567f)

Author: mikehearn

Diff for: docs/user/Modules.md

@@ -69,10 +69,11 @@ Note that the ES module file has `.mjs` extension.
 Also note that the `allowIO()` option is provided to enable IO access.
 More examples of ES modules usage are available [here](https://github.com/oracle/graaljs/blob/master/graal-js/src/com.oracle.truffle.js.test/src/com/oracle/truffle/js/test/interop/ESModuleTest.java).
 
-#### Experimental module namespace exports
+#### Module namespace exports
 
-The `--js.esm-eval-returns-exports` experimental option can be used to expose the ES module namespace exported object to a Polyglot `Context`.
+The `--js.esm-eval-returns-exports` option (off by default) can be used to expose the ES module namespace exported object to a Polyglot `Context`.
 This can be handy when an ES module is used directly from Java:
+
 ```java
 public static void main(String[] args) throws IOException {
 
@@ -92,8 +93,6 @@ public static void main(String[] args) throws IOException {
     System.out.println(exports.getMember("foo").toString()); // prints `42`
 }
 ```
-The option is disabled by default.
-
 
 ### Truffle FileSystem
 

Diff for: docs/user/Options.md

@@ -73,6 +73,7 @@ The following stable options are frequently relevant:
    * `--js.allow-eval`: allow the code generation from strings, e.g. using `eval()` or the `Function` constructor. Boolean value, default is `true`.
    * `--js.timer-resolution`: sets the resolution of timing functions, like `Date.now()` and `performance.now()`, in nanoseconds. Default: `1000000` (i.e. 1 ms).
    * `--js.unhandled-rejections`: configure unhandled promise rejection tracking. Accepted values are `none` (default, no tracking), `warn` (print a warning to stderr), `throw` (throw an exception), and `handler` (invoke a custom handler).
+   * `--js.esm-eval-returns-exports`: `context.eval` of an ES module `Source` returns its exported symbols.
 
 For a complete list, use `js --help:js:internal`
 
@@ -116,6 +117,5 @@ To use them, the `--experimental-options` flag is required or the experimental o
    * `--js.nashorn-compat`: provide compatibility mode with the Nashorn engine. Sets ECMAScript version to 5 by default. Might conflict with newer ECMAScript versions. Boolean value, default is `false`.
    * `--js.timezone`: set the local time zone. String value, default is the system default.
    * `--js.v8-compat`: provide better compatibility with Google's V8 engine. Boolean value, default is `false`.
-   * `--js.esm-eval-returns-exports`: `context.eval` of an ES module `Source` returns its exported symbols.
-   * `--js.temporal`: enable  [`Temporal` API](https://github.com/tc39/proposal-temporal).
+   * `--js.temporal`: enable [`Temporal` API](https://github.com/tc39/proposal-temporal).
    * `--js.webassembly`: enable `WebAssembly` API.

Diff for: graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/JSContextOptions.java

@@ -639,7 +639,7 @@ public String toString() {
     @CompilationFinal private boolean wasmBigInt;
 
     public static final String ESM_EVAL_RETURNS_EXPORTS_NAME = JS_OPTION_PREFIX + "esm-eval-returns-exports";
-    @Option(name = ESM_EVAL_RETURNS_EXPORTS_NAME, category = OptionCategory.EXPERT, help = "Eval of an ES module through the polyglot API returns its exported symbols.") //
+    @Option(name = ESM_EVAL_RETURNS_EXPORTS_NAME, category = OptionCategory.EXPERT, stability = OptionStability.STABLE, sandbox = SandboxPolicy.UNTRUSTED, help = "Eval of an ES module through the polyglot API returns its exported symbols.") //
     public static final OptionKey<Boolean> ESM_EVAL_RETURNS_EXPORTS = new OptionKey<>(false);
     @CompilationFinal private boolean esmEvalReturnsExports;