I added methods to check for valid version and optimization levels that

Rhino embeddings can use to check the validity of data.

js/rhino/src/org/mozilla/javascript/Context.java

@@ -771,7 +771,7 @@ public class Context
         this.version = version;
     }
 
-    static void checkLanguageVersion(int version)
+    public static boolean isValidLanguageVersion(int version)
     {
         switch (version) {
             case VERSION_DEFAULT:
@@ -782,6 +782,14 @@ public class Context
             case VERSION_1_4:
             case VERSION_1_5:
             case VERSION_1_6:
+                return true;
+        }
+        return false;
+    }
+
+    public static void checkLanguageVersion(int version)
+    {
+        if (isValidLanguageVersion(version)) {
             return;
         }
         throw new IllegalArgumentException("Bad language version: "+version);
@@ -1841,9 +1849,16 @@ public class Context
         this.optimizationLevel = optimizationLevel;
     }
 
-    static void checkOptimizationLevel(int optimizationLevel)
+    public static boolean isValidOptimizationLevel(int optimizationLevel)
     {
-        if (!(-1 <= optimizationLevel && optimizationLevel <= 9))
+        return -1 <= optimizationLevel && optimizationLevel <= 9;
+    }
+
+    public static void checkOptimizationLevel(int optimizationLevel)
+    {
+        if (isValidOptimizationLevel(optimizationLevel)) {
+            return;
+        }
         throw new IllegalArgumentException(
             "Optimization level outside [-1..9]: "+optimizationLevel);
     }