fixes #169: throw a RangeError in take/drop when input is NaN-ish (#181)

spec.html

@@ -533,7 +533,9 @@ <h1>%Iterator.prototype%.filter ( _filterer_ )</h1>
         <h1>%Iterator.prototype%.take ( _limit_ )</h1>
         <emu-alg>
           1. Let _iterated_ be ? GetIteratorDirect(*this* value).
-          1. Let _integerLimit_ be ? ToIntegerOrInfinity(_limit_).
+          1. Let _numLimit_ be ? ToNumber(_limit_).
+          1. If _numLimit_ is *NaN*, throw a *RangeError* exception.
+          1. Let _integerLimit_ be ! ToIntegerOrInfinity(_numLimit_).
           1. If _integerLimit_ &lt; 0, throw a *RangeError* exception.
           1. Let _closure_ be a new Abstract Closure with no parameters that captures _iterated_ and _integerLimit_ and performs the following steps when called:
             1. Let _remaining_ be _integerLimit_.
@@ -555,7 +557,9 @@ <h1>%Iterator.prototype%.take ( _limit_ )</h1>
         <h1>%Iterator.prototype%.drop ( _limit_ )</h1>
         <emu-alg>
           1. Let _iterated_ be ? GetIteratorDirect(*this* value).
-          1. Let _integerLimit_ be ? ToIntegerOrInfinity(_limit_).
+          1. Let _numLimit_ be ? ToNumber(_limit_).
+          1. If _numLimit_ is *NaN*, throw a *RangeError* exception.
+          1. Let _integerLimit_ be ! ToIntegerOrInfinity(_numLimit_).
           1. If _integerLimit_ &lt; 0, throw a *RangeError* exception.
           1. Let _closure_ be a new Abstract Closure with no parameters that captures _iterated_ and _integerLimit_ and performs the following steps when called:
             1. Let _remaining_ be _integerLimit_.