Drop dependency from `mruby-array-ext` to `mruby-enum-ext`

mrbgems/mruby-array-ext/mrbgem.rake

@@ -2,5 +2,4 @@ MRuby::Gem::Specification.new('mruby-array-ext') do |spec|
   spec.license = 'MIT'
   spec.author  = 'mruby developers'
   spec.summary = 'Array class extension'
-  spec.add_test_dependency 'mruby-enumerator', core: 'mruby-enumerator'
 end

mrbgems/mruby-array-ext/mrblib/array.rb

@@ -903,8 +903,8 @@ class Array
     column_count = nil
     self.each do |row|
       raise TypeError unless row.is_a?(Array)
-      column_count ||= row.count
-      raise IndexError, 'element size differs' unless column_count == row.count
+      column_count ||= row.size
+      raise IndexError, 'element size differs' unless column_count == row.size
     end
 
     Array.new(column_count) do |column_index|