ScriptEngine of Graal.js should use Nashorn-compatibility options.

PullRequest: js/407

CHANGELOG.md

@@ -8,6 +8,7 @@ The main focus is on user-observable behavior of the engine.
 * Add support for `String.prototype.matchAll`, a Stage 3 proposal.
 * Implement optional catch binding proposal, targeted for ES2019.
 * removed legacy `NashornExtensions` option, use `--js.nashorn-compat` instead.
+* Nashorn compatibility mode was turned on for ScriptEngine provided by Graal JavaScript.
 
 ## Version 1.0.0 RC4
 * Added stack trace limit option (--js.stack-trace-limit).

docs/user/NashornMigrationGuide.md

@@ -31,6 +31,7 @@ Note that, depending on the build setup, GraalVM might still ship Nashorn and it
 
 ### ScriptEngine name `graal.js`
 Graal JavaScript is shipped with ScriptEngine support.
+Nashorn compatibility mode is turned on for this ScriptEngine.
 It registers under several names, including `graal.js`.
 Depending on the build setup, GraalVM might still ship Nashorn and provide it via ScriptEngine.
 

graal-js/src/com.oracle.truffle.js.scriptengine/src/com/oracle/truffle/js/scriptengine/GraalJSScriptEngine.java

@@ -92,7 +92,7 @@ public final class GraalJSScriptEngine extends AbstractScriptEngine implements C
         Context.Builder contextConfigToUse = contextConfig;
         if (contextConfigToUse == null) {
             // default config
-            contextConfigToUse = Context.newBuilder(ID).allowHostAccess(true).allowCreateThread(true);
+            contextConfigToUse = Context.newBuilder(ID).allowHostAccess(true).allowCreateThread(true).option("js.nashorn-compat", "true").option("js.syntax-extensions", "true");
         }
         this.factory = new GraalJSEngineFactory(engineToUse);
         this.contextConfig = contextConfigToUse.engine(engineToUse);