Fix Any json encoding/decoding for ruby. (#5592)

* Fix Any json encoding/decoding for ruby.

* Revert unnecessary changes
diff --git a/ruby/tests/encode_decode_test.rb b/ruby/tests/encode_decode_test.rb
index d2b25fd..d3cebab 100644
--- a/ruby/tests/encode_decode_test.rb
+++ b/ruby/tests/encode_decode_test.rb
@@ -22,8 +22,8 @@
 
     # Test discard unknown for singular message field.
     unknown_msg = A::B::C::TestUnknown.new(
-	    :optional_unknown =>
-	    A::B::C::TestUnknown.new(:unknown_field => 1))
+            :optional_unknown =>
+            A::B::C::TestUnknown.new(:unknown_field => 1))
     from = A::B::C::TestUnknown.encode(unknown_msg)
     m = A::B::C::TestMessage.decode(from)
     Google::Protobuf.discard_unknown(m)
@@ -32,8 +32,8 @@
 
     # Test discard unknown for repeated message field.
     unknown_msg = A::B::C::TestUnknown.new(
-	    :repeated_unknown =>
-	    [A::B::C::TestUnknown.new(:unknown_field => 1)])
+            :repeated_unknown =>
+            [A::B::C::TestUnknown.new(:unknown_field => 1)])
     from = A::B::C::TestUnknown.encode(unknown_msg)
     m = A::B::C::TestMessage.decode(from)
     Google::Protobuf.discard_unknown(m)
@@ -42,8 +42,8 @@
 
     # Test discard unknown for map value message field.
     unknown_msg = A::B::C::TestUnknown.new(
-	    :map_unknown =>
-	    {"" => A::B::C::TestUnknown.new(:unknown_field => 1)})
+            :map_unknown =>
+            {"" => A::B::C::TestUnknown.new(:unknown_field => 1)})
     from = A::B::C::TestUnknown.encode(unknown_msg)
     m = A::B::C::TestMessage.decode(from)
     Google::Protobuf.discard_unknown(m)
@@ -52,8 +52,8 @@
 
     # Test discard unknown for oneof message field.
     unknown_msg = A::B::C::TestUnknown.new(
-	    :oneof_unknown =>
-	    A::B::C::TestUnknown.new(:unknown_field => 1))
+            :oneof_unknown =>
+            A::B::C::TestUnknown.new(:unknown_field => 1))
     from = A::B::C::TestUnknown.encode(unknown_msg)
     m = A::B::C::TestMessage.decode(from)
     Google::Protobuf.discard_unknown(m)