quick fix to part of new issue in #1099:

`not in []` unconditionally compiled to `false`

Author: michaelficarra

lib/coffee-script/nodes.js

@@ -1408,11 +1408,11 @@ exports.In = class In extends Base
     @compileLoopTest o
 
   compileOrTest: (o) ->
+    return "#{!!@negated}" if @array.base.objects.length is 0
     [sub, ref] = @object.cache o, LEVEL_OP
     [cmp, cnj] = if @negated then [' !== ', ' && '] else [' === ', ' || ']
     tests = for item, i in @array.base.objects
       (if i then ref else sub) + cmp + item.compile o, LEVEL_ACCESS
-    return 'false' if tests.length is 0
     tests = tests.join cnj
     if o.level < LEVEL_OP then tests else "(#{tests})"
 

src/nodes.coffee

@@ -199,16 +199,19 @@ test "#1100: precedence in or-test compilation of `in`", ->
 
 test "#1630: `in` should check `hasOwnProperty`", ->
   ok undefined not in length: 1
-  
+
 test "#1714: lexer bug with raw range `for` followed by `in`", ->
   0 for [1..2]
   ok not ('a' in ['b'])
-  
+
   0 for [1..2]; ok not ('a' in ['b'])
-  
+
   0 for [1..10] # comment ending
   ok not ('a' in ['b'])
 
+test "#1099: statically determined `not in []` reporting incorrect result", ->
+  ok 0 not in []
+
 
 # Chained Comparison
 
@@ -259,4 +262,4 @@ test "#1102: String literal prevents line continuation", ->
 
 test "#1703, ---x is invalid JS", ->
   x = 2
-  eq (- --x), -1
+  eq (- --x), -1