Improve the performance of HWIDA `select` and `reject`

These are (potentially, depending on input) called in several places in
both the router, and Active Record. The code also becomes much cleaner.
This results in ~33% performance gain in both methods.

    Calculating -------------------------------------
                  before    15.696k i/100ms
                  after     19.865k i/100ms
    -------------------------------------------------
                  before    303.064k (± 2.6%) i/s -      1.523M
                  after     446.734k (± 2.4%) i/s -      2.245M

On Ruby 2.2, a warning will be emitted about states not being copied,
because we're calling `super` from a subclass. We can safely ignore it,
however, since we're converting the result back into a HWIDA

1 files changed, 4 insertions, 4 deletions

diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index 4f71f13971..c7477b9ff4 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -237,12 +237,12 @@ module ActiveSupport
     def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
     def to_options!; self end
 
-    def select(*args, &block)
-      dup.tap { |hash| hash.select!(*args, &block) }
+    def select(*)
+      super.with_indifferent_access
     end
 
-    def reject(*args, &block)
-      dup.tap { |hash| hash.reject!(*args, &block) }
+    def reject(*)
+      super.with_indifferent_access
     end
 
     # Convert to a regular hash with string keys.