Fix typo in test
Fixes Dependency bug in Active Support

DateTime defined in date.rb
Merge pull request #10414 from eiel/fix_dependency

Fixes Dependency bug in Active Support
Merge pull request #10412 from vipulnsward/fix_callback_test_typo

Fix typo in test
Add test for `AR::Base#to_param`

According to the doc of `AR::Base#to_param`(
https://github.com/rails/rails/blob/04cda1848cb847c2bdad0bfc12160dc8d554
7775/activerecord/lib/active_record/integration.rb#L18 ), it returns
`nil` if the record is not persisted.
Merge pull request #10416 from tkhr/add-test-for-AR--Base#to_param

Add test for `AR::Base#to_param`
rake:db:test:prepare falls back to original environment after execution.
Refactoring the creation of TestTasks to remove code duplication.
Add styling to h1
Merge pull request #10423 from wangjohn/refactoring_testing_rakefile

Refactoring the creation of TestTasks to remove code duplication.
Merge pull request #10426 from tkrajcar/rescue-h1-fix

Add styling to h1 for default rescue layout
Add parameter :sslcompression to PostgreSQL adapter.

It is new in PostgreSQL-9.2 .
Merge pull request #10430 from larskanis/add_sslcompression_to_pg_adapter

Add parameter :sslcompression to PostgreSQL adapter.
Improving the performance of callbacks by keeping a hash of the
callbacks in the CallbackChain, so you don't have to iterate over all
callbacks when checking for duplicates.

Benchmark results when the tests in
activerecord/test/cases/associations_test.rb were run with and without
the change:

== On master (when scanning all of the callbacks):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------

  1.85     9.26      0.82    18412     0.04     0.05
ActiveSupport::Callbacks::Callback#matches?
  1.22    12.32      0.54    18412     0.03     0.08
ActiveSupport::Callbacks::Callback#duplicates?
  0.93    14.61      0.41    19600     0.02     0.21
ActiveSupport::Callbacks::CallbackChain#remove_duplicates

Finished tests in 1.217065s, 30.4010 tests/s, 53.4072 assertions/s.
 ---------------------------------------------------------

== On my branch (when using a hash to check callback duplication):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------
  0.15    29.63      0.06     1188     0.05     0.72
ActiveSupport::Callbacks::CallbackChain#handle_duplicates
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#matches?
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#duplicates?
  0.00    40.50      0.00       91     0.00     0.22
ActiveSupport::Callbacks::CallbackChain#scan_and_remove_duplicates

Finished tests in 1.117757s, 33.1020 tests/s, 58.1522 assertions/s.
 ---------------------------------------------------------
Merge pull request #10433 from wangjohn/making_callbacks_more_performant

Improving the performance of callbacks
Merge pull request #10424 from markevich/fix_test_prepare

Restore ActiveRecord connection to original environment after rake:db:test:prepare task.