ADS1115 : measuring 5v voltages and powering with 3.3v
Is your arrangement bsafsm Yes, perfectly.

Is your arrangement a good idea? No, it is not.

When the ADS1115 is run at 5V it needs at least 3.5V on the I2C bus to properly register a HIGH.  

However you can pull up to 5v instead and you won't have a problem.  Not only is the esp8255 tolerant of 5v, but that 5v is severely limited in current by the pull-up resistors, so even non tolerant inputs would have a hard time complaining. Worst case scenario, the ESP8266 pulls the bus down to maybe 3.8v (3.3v plus an ESD diode drop) which is fine for a logic high on the ADS1115.

However, if you want to do things properly, you really should use a proper I2C level translator.