unexpected "^F" after hitting <enter> to make a new line when editing html file

[yaroot]

Every time I hit to make a new line, there's a "^F" appears at the end of the last line. This only occurs when editing html file.
After some digging I find this line was the cause:
inoremap neocomplcache#smart_close_popup() . (&indentexpr != '' ? "X":"")
It suppose to close the popup and make a new line, right?

[Shougo]

Please use this.

" : close popup and save indent.
inoremap neocomplcache#smart_close_popup() . ""

[yaroot]

thanks, works great!