Fix potion transformer to look up the right name depending on context.

Signed-off-by: cpw <cpw+github@weeksfamily.ca>

src/main/resources/META-INF/fieldtomethodtransformers.js

@@ -7,7 +7,8 @@ function initializeCoreMod() {
             },
             'transformer': function(classNode) {
                 var asmapi=Java.type('net.minecraftforge.coremod.api.ASMAPI')
-                asmapi.redirectFieldToMethod(classNode, 'potion', 'getPotionRaw')
+                var fn = asmapi.mapField('field_188420_b') // potion field - remap to mcp if necessary
+                asmapi.redirectFieldToMethod(classNode, fn, 'getPotionRaw')
                 return classNode;
             }
         }