Provide access to logger instance within TaggedLogging blocks

this improves encapsulation, simplifying occurrences like the following:

    Rails.logger.tagged("DEBUG") { Rails.logger.debug(msg) }

... by removing the need to rely on (i.e. repeat) outer variables:

    Rails.logger.tagged("DEBUG") { |logger| logger.debug(msg) }

activesupport/lib/active_support/tagged_logging.rb

@@ -45,7 +45,7 @@ def tagged(*new_tags)
       tags     = formatter.current_tags
       new_tags = new_tags.flatten.reject(&:blank?)
       tags.concat new_tags
-      yield
+      yield self
     ensure
       tags.pop(new_tags.size)
     end

activesupport/test/tagged_logging_test.rb

@@ -18,7 +18,7 @@ def flush(*)
     @logger.tagged("BCX") { @logger.info "Funky time" }
     assert_equal "[BCX] Funky time\n", @output.string
   end
-  
+
   test "tagged twice" do
     @logger.tagged("BCX") { @logger.tagged("Jason") { @logger.info "Funky time" } }
     assert_equal "[BCX] [Jason] Funky time\n", @output.string
@@ -29,6 +29,11 @@ def flush(*)
     assert_equal "[BCX] [Jason] [New] Funky time\n", @output.string
   end
 
+  test "provides access to the logger instance" do
+    @logger.tagged("BCX") { |logger| logger.info "Funky time" }
+    assert_equal "[BCX] Funky time\n", @output.string
+  end
+
   test "tagged once with blank and nil" do
     @logger.tagged(nil, "", "New") { @logger.info "Funky time" }
     assert_equal "[New] Funky time\n", @output.string