Don't compile functions in a context the caller doesn't have access to

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 34c35031b2601dd4c1ef614c877668d307502569..10a0566c295cb4d0dc6ffd3f171141ef97787fed 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -1779,7 +1779,9 @@ function FunctionConstructor(arg1) {  // length == 1
   var global_proxy = %GlobalProxy(FunctionConstructor);
   // Compile the string in the constructor and not a helper so that errors
   // appear to come from here.
-  var f = %_CallFunction(global_proxy, %CompileString(source, true));
+  var f = %CompileString(source, true);
+  if (!IS_FUNCTION(f)) return f;
+  f = %_CallFunction(global_proxy, f);
   %FunctionMarkNameShouldPrintAsAnonymous(f);
   return f;
 }