check for infinite numbers when encoding Floats to JSon

std/Math.hx

@@ -32,6 +32,7 @@ extern class Math
 		
 		For example, this is the result of -1.0 / 0.0.
 		
+		Operations with NEGATIVE_INFINITY as an operand may result in
 		Operations with NEGATIVE_INFINITY as an operand may result in
 		NEGATIVE_INFINITY, POSITIVE_INFINITY or NaN. For detailed information,
 		see ...
@@ -50,8 +51,8 @@ extern class Math
 		see ...
 	
 		If this constant is converted to an Int, e.g. through Std.int(), the
-		result is unspecified.		
-	**/	
+		result is unspecified.
+	**/
 	static var POSITIVE_INFINITY(default,null) : Float;
 
 	/**
@@ -64,7 +65,7 @@ extern class Math
 		All further operations with NaN as an operand will result in NaN.
 		
 		If this constant is converted to an Int, e.g. through Std.int(), the
-		result is unspecified.		
+		result is unspecified.
 	**/
 	static var NaN(default, null) : Float;
 
@@ -100,7 +101,7 @@ extern class Math
 		If [a] or [b] are POSITIVE_INFINITY, the result is POSITIVE_INFINITY.
 		
 		If [a] and [b] are NEGATIVE_INFINITY, the result is NEGATIVE_INFINITY.
-	**/	
+	**/
 	static function max(a:Float, b:Float):Float;
 	
 	/**
@@ -118,7 +119,7 @@ extern class Math
 		The unit of [v] is radians.
 		
 		If [v] is NaN or infinite, the result is NaN.
-	**/	
+	**/
 	static function cos(v:Float):Float;
 	
 	// TODO
@@ -190,7 +191,7 @@ extern class Math
 		Returns the smallest Int value that is not less than [v].
 		
 		TODO: need spec
-	**/	
+	**/
 	static function ceil(v:Float):Int;
 	
 	/**

std/haxe/Json.hx

@@ -102,7 +102,7 @@ class Json {
 		case TInt:
 			add(v);
 		case TFloat:
-			add(v+1==v ? null : v);
+			add(Math.isFinite(v) ? v : 'null');
 		case TFunction:
 			add('"<fun>"');
 		case TClass(c):

tests/unit/TestMisc.hx

@@ -562,6 +562,9 @@ class TestMisc extends Test {
 
 		eq( haxe.Json.parse('"\\u00E9"'), "é" );
 
+		eq(haxe.Json.stringify(Math.POSITIVE_INFINITY), "null");
+		eq(haxe.Json.stringify(Math.NEGATIVE_INFINITY), "null");
+		eq(haxe.Json.stringify(Math.NaN), "null");
 	}
 
 	function testConstructorsOpts() {