Understanding whitespace

I have a piece of text that I am parsing that looks like this:
c: winsize0 is {"1919","1925","1936"}

The above rule matches fine with the rule IFSTATEMENT:
VARIABLE 	: /\w[a-z0-9-\/]*/i 	
DOMAIN_COMP	: /is\s+[not]*/ix
DOMAIN	 	: VALUES(s)  # {"vsk", "vr", ...}
IFSTATEMENT	: VARIABLE DOMAIN_COMP '{' DOMAIN '}'

My question is how to continue to get a match with:
c: winsize0 is{"1919","1925","1936"}

Notice the missing space between the is and the '{'

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