E.memoryArea not working on ESP8266 (due to char-iterator ?)

Let me try to give a better explanation. Its more or less a proof of concept.
The idea behind is to use it like a "firmware-extension".
First of all, I made some changes to Espruino firmware:

• new code for handling strings in flash http://forum.espruino.com/comments/12709163/
  
• added functions for a kind of housekeeping in a flash page.
  
• Start of page is 4 bytes for each string, first 2 bytes are relative start, next 2 bytes are length
  
• http://jumspruino.jumware.com/sources/flashMemory/jswrap_FlashExtension.h
  
• http://jumspruino.jumware.com/sources/flashMemory/jswrap_FlashExtension.c
  Next created a nodejs application to build a page for flash.
  My idea is to make this available some day.
  Today my learning curve is still steeply rising, got my public virtual server some days ago ....
  Could give access right now on a personal base only :-(
  Writing this to flash is done with nodemcu firmware programmer.
  Data is written to 0x71000 and/or 0x72000, since this is the first empty page I found.
  Source for 1st test with function and object. Only removed module-relevant commands
  
• SHA1 function http://jumspruino.jumware.com/sources/http/SHA1.js
  
• http-server object http://jumspruino.jumware.com/sources/http/EspSrv.js
  
• test itself http://jumspruino.jumware.com/sources/flashMemory/Test1.js
  Source for 2nd test
  
• SHA1 sourcecode http://jumspruino.jumware.com/sources/flashMemory/SHA1.js
  
• test itself http://jumspruino.jumware.com/sources/flashMemory/Test2.js