Support decimal percentages for font size

Author: tneotia

lib/src/css_parser.dart

@@ -621,7 +621,7 @@ class ExpressionMapping {
     if (value is css.NumberTerm) {
       return FontSize(double.tryParse(value.text));
     } else if (value is css.PercentageTerm) {
-      return FontSize.percent(int.tryParse(value.text)!);
+      return FontSize.percent(double.tryParse(value.text)!);
     } else if (value is css.EmTerm) {
       return FontSize.em(double.tryParse(value.text));
     } else if (value is css.RemTerm) {

lib/style.dart

@@ -473,8 +473,8 @@ class FontSize {
   const FontSize(this.size, {this.units = ""});
 
   /// A percentage of the parent style's font size.
-  factory FontSize.percent(int percent) {
-    return FontSize(percent.toDouble() / -100.0, units: "%");
+  factory FontSize.percent(double percent) {
+    return FontSize(percent / -100.0, units: "%");
   }
 
   factory FontSize.em(double? em) {