Remove bignum warnings

test/json/json_parser_test.rb:141: warning: Integer out of Float range
lib/json/common.rb:353: warning: Float 12345678901234567890... out of range

Author: etiennebarrie

test/json/json_parser_test.rb

@@ -138,7 +138,8 @@ def test_parse_bignum
 
     bignum = Integer('1234567890' * 50)
     assert_equal(bignum, JSON.parse(bignum.to_s))
-    assert_equal(bignum.to_f, JSON.parse(bignum.to_s + ".0"))
+    bignum_float = EnvUtil.suppress_warning { bignum.to_f }
+    assert_equal(bignum_float, EnvUtil.suppress_warning { JSON.parse(bignum.to_s + ".0") })
   end
 
   def test_parse_bigdecimals