Introduce createIsolate to make use of shared sealed scopes easier.

Author: aardvark179

rhino/src/main/java/org/mozilla/javascript/TopLevel.java

@@ -118,6 +118,23 @@ public TopLevel(ScriptableObject customGlobal) {
         globalThis = customGlobal;
     }
 
+    public TopLevel createIsolate() {
+        var newGlobal = new NativeObject();
+        newGlobal.setPrototype(getGlobalThis());
+        newGlobal.setParentScope(null);
+        var isolate = new TopLevel(newGlobal);
+        isolate.cacheBuiltins(newGlobal, false);
+        return isolate;
+    }
+
+    public TopLevel createIsolate(ScriptableObject customGlobal) {
+        customGlobal.setParentScope(null);
+        customGlobal.setPrototype(getGlobalThis());
+        var isolate = new TopLevel(customGlobal);
+        isolate.cacheBuiltins(customGlobal, false);
+        return isolate;
+    }
+
     @Override
     public String getClassName() {
         return "topLevel";

tests/src/test/java/org/mozilla/javascript/drivers/ScriptTestsBase.java

@@ -71,9 +71,7 @@ private Object executeRhinoScript(boolean interpretedMode) {
             Global global = new Global(cx);
             loadNatives(global);
 
-            Scriptable scope = cx.newObject(global);
-            scope.setPrototype(global);
-            scope.setParentScope(null);
+            var scope = global.createIsolate();
 
             return cx.evaluateReader(scope, script, suiteName, 1, null);
         } catch (JavaScriptException ex) {

tests/src/test/java/org/mozilla/javascript/tests/SealedSharedScopeTest.java

@@ -21,9 +21,7 @@
 import org.mozilla.javascript.EvaluatorException;
 import org.mozilla.javascript.IdFunctionObject;
 import org.mozilla.javascript.ImporterTopLevel;
-import org.mozilla.javascript.NativeObject;
 import org.mozilla.javascript.Scriptable;
-import org.mozilla.javascript.TopLevel;
 import org.mozilla.javascript.Wrapper;
 
 @RunWith(BlockJUnit4ClassRunner.class)
@@ -43,12 +41,8 @@ public void setUp() throws Exception {
 
         ctx = Context.enter();
         ctx.setLanguageVersion(Context.VERSION_DEFAULT);
-        var scope1Global = new NativeObject();
-        scope1Global.setPrototype(sharedScope.getGlobalThis());
-        scope1 = new TopLevel(scope1Global);
-        var scope2Global = new NativeObject();
-        scope2Global.setPrototype(sharedScope.getGlobalThis());
-        scope2 = new TopLevel(scope2Global);
+        scope1 = sharedScope.createIsolate();
+        scope2 = sharedScope.createIsolate();
     }
 
     @After