Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb

Index: third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb
diff --git a/third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb b/third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb
index 11d6c2eb8cba3386076673f5852ac98e4b9d8c13..0ad2060d433293defe4d281b813714c5021a1286 100644
--- a/third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb
+++ b/third_party/protobuf/ruby/lib/google/protobuf/repeated_field.rb
@@ -74,7 +74,7 @@ module Google
         :include?, :index, :inspect, :join,
         :pack, :permutation, :product, :pretty_print, :pretty_print_cycle,
         :rassoc, :repeated_combination, :repeated_permutation, :reverse,
-        :rindex, :rotate, :sample, :shuffle, :shelljoin,
+        :rindex, :rotate, :sample, :shuffle, :shelljoin, :slice,
         :to_s, :transpose, :uniq, :|
 
 
@@ -173,7 +173,7 @@ module Google
           external_enumerator.each_with_index do |val, i|
             result = yield(val)
             results << result
-            #nil means no change occurred from yield; usually occurs when #to_a is called
+            #nil means no change occured from yield; usually occurs when #to_a is called
             if result
               repeated_field[i] = result if result != val
             end