Ruby prof fixes

[arunagw]

finally got green build with ruby-prof changes.

second commit fixes

/Users/arunagw/checkouts/rails/actionpack/lib/action_view/helpers/number_helper.rb:257:in `number_with_delimiter': undefined method `safe_join' for #<ActiveSupport::Testing::Performance::Metrics::Objects:0x007f97305de098> (NoMethodError)
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:242:in `format'
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:105:in `report'
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:91:in `run_profile'
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:45:in `block in run'
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:43:in `each'
    from /Users/arunagw/checkouts/rails/activesupport/lib/active_support/testing/performance.rb:43:in `run'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:787:in `block in _run_suite'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:780:in `map'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:780:in `_run_suite'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:770:in `block in _run_suites'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:770:in `map'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:770:in `_run_suites'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:746:in `_run_anything'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:909:in `run_tests'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:896:in `block in _run'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:895:in `each'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:895:in `_run'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:884:in `run'
    from /Users/arunagw/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/minitest/unit.rb:664:in `block in autorun'
[[:puke, [ApplicationTests::TestTest, "test_performance_test", #<MiniTest::Assertion: Run options: --seed 42815

[carlosantoniodasilva]

Thanks!