Initial Value:

adaptive-fill-regexp is a variable defined in `fill.el'.
Its value is 
"[ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*"


Value after opening one PHP file:

adaptive-fill-regexp is a variable defined in `fill.el'.
Its value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)"
Local in buffer AgencyStudentController.php; global value is 
"[ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*"


Value after opening another file (this with mixed PHP, HTML & Javascript):

adaptive-fill-regexp is a variable defined in `fill.el'.
Its value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)"
Local in buffer create.php; global value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)\\)"


Value after navigating into some JS:
adaptive-fill-regexp is a variable defined in `fill.el'.
Its value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)\\)\\)"


After this the mode would not change to nXhtml or PHP mode unless I started entering characters.

Once I did that in a PHP chunk:

adaptive-fill-regexp is a variable defined in `fill.el'.
Its value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)\\)\\)\\)"
Local in buffer create.php; global value is 
"[ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\(//+\\|\\**\\)[ 	]*\\([ 	]*\\([-!|#%;>*·•‣⁃◦]+[ 	]*\\)*\\)\\)\\)"