BUGFIX Fixed NumericField->jsValidation(), now accepts negative numbe…

…rs, making it more like the equivalent phpValidation(), which is using is_numeric() (see #4874, thanks Allisone) (from r97482)

git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@102497 467b73ca-7a2a-4603-9d3b-597d59a354a9

forms/NumericField.php

@@ -24,7 +24,7 @@ function jsValidation() {
 				el = _CURRENT_FORM.elements[fieldName];
 				if(!el || !el.value) return true;
 				
-			 	if(el.value.match(/^\s*([0-9]+(\.[0-9]+)?\s*$)/)) { 
+			 	if(el.value.match(/^\s*(\-?[0-9]+(\.[0-9]+)?\s*$)/)) { 
 			 		return true;
 			 	} else {
 					validationError(el, "'" + el.value + "' $error","validation");