Speed up Array#split

Ruby 2.0.0p247
Rehearsal ---------------------------------------
old  10.670000   0.150000  10.820000 ( 10.822651)
new   8.520000   0.050000   8.570000 (  8.571825)
----------------------------- total: 19.390000sec

          user     system      total        real
old  10.620000   0.170000  10.790000 ( 10.790409)
new   8.570000   0.110000   8.680000 (  8.686051)

activesupport/lib/active_support/core_ext/array/grouping.rb

@@ -83,10 +83,10 @@ def in_groups(number, fill_with = nil)
   #
   #   [1, 2, 3, 4, 5].split(3)              # => [[1, 2], [4, 5]]
   #   (1..10).to_a.split { |i| i % 3 == 0 } # => [[1, 2], [4, 5], [7, 8], [10]]
-  def split(value = nil, &block)
-    if block
+  def split(value = nil)
+    if block_given?
       inject([[]]) do |results, element|
-        if block.call(element)
+        if yield(element)
           results << []
         else
           results.last << element