Removes an unused gas from the code

I have no idea why this is in the code.
Its unobtainable in game and would be difficult to create even with
admin powers, as there's no canister to spawn it in or anything like
that so you'd have to VV an already existing gas.

code/ATMOSPHERICS/components/trinary_devices/filter.dm

@@ -40,7 +40,7 @@
 	..()
 	switch(filter_type)
 		if(0) //removing hydrocarbons
-			filtered_out = list("phoron", "oxygen_agent_b")
+			filtered_out = list("phoron")
 		if(1) //removing O2
 			filtered_out = list("oxygen")
 		if(2) //removing N2
@@ -95,10 +95,10 @@
 
 /obj/machinery/atmospherics/trinary/filter/process()
 	..()
-	
+
 	last_power_draw = 0
 	last_flow_rate = 0
-	
+
 	if((stat & (NOPOWER|BROKEN)) || !use_power)
 		return
 

code/defines/gases.dm

@@ -21,11 +21,11 @@
 /decl/xgm_gas/phoron
 	id = "phoron"
 	name = "Phoron"
-	
+
 	//Note that this has a significant impact on TTV yield.
 	//Because it is so high, any leftover phoron soaks up a lot of heat and drops the yield pressure.
 	specific_heat = 200	// J/(mol*K)
-	
+
 	//Hypothetical group 14 (same as carbon), period 8 element.
 	//Using multiplicity rule, it's atomic number is 162
 	//and following a N/Z ratio of 1.5, the molar mass of a monatomic gas is:
@@ -51,9 +51,3 @@
 
 	tile_overlay = "sleeping_agent"
 	overlay_limit = 1
-
-/decl/xgm_gas/oxygen_agent_b
-	id = "oxygen_agent_b"
-	name = "Oxygen Agent-B"	//what is this?
-	specific_heat = 300	// J/(mol*K)
-	molar_mass = 0.032	// kg/mol

code/game/machinery/atmoalter/scrubber.dm

@@ -17,7 +17,7 @@
 	var/minrate = 0
 	var/maxrate = 10 * ONE_ATMOSPHERE
 
-	var/list/scrubbing_gas = list("phoron", "carbon_dioxide", "sleeping_agent", "oxygen_agent_b")
+	var/list/scrubbing_gas = list("phoron", "carbon_dioxide", "sleeping_agent")
 
 /obj/machinery/portable_atmospherics/powered/scrubber/New()
 	..()