Rewrite csslib's hexToInt

pkg/csslib/lib/src/property.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /** Representations of CSS styles. */
 
 part of csslib.parser;
 
 // TODO(terry): Prune down this file we do need some of the code in this file
 //              for darker, lighter, how to represent a Font, etc but alot of
@@ skipping 273 matching lines @@
           return new Hsla(args[0], args[1], args[2],
               args[3]).toHexArgbString();
         default:
           // Type not defined UnsupportedOperationException should have thrown.
           assert(true);
           break;
       }
     }
   }
 
-  /**
-   * [hex] hexadecimal string to convert to scalar.
-   * returns hexadecimal number as an integer.
-   * throws BadNumberFormatException if [hex] isn't a valid hexadecimal number.
-   */
-  // TODO(terry): Should be part of Dart standard library see bug
-  // <http://code.google.com/p/dart/issues/detail?id=2624>
-  static int hexToInt(String hex) {
-    int val = 0;
-
-    int len = hex.length;
-    for (int i = 0; i < len; i++) {
-      int hexDigit = hex.codeUnitAt(i);
-      if (hexDigit >= 48 && hexDigit <= 57) {
-        val += (hexDigit - 48) * (1 << (4 * (len - 1 - i)));
-      } else if (hexDigit >= 65 && hexDigit <= 70) {
-        // A..F
-        val += (hexDigit - 55) * (1 << (4 * (len - 1 - i)));
-      } else if (hexDigit >= 97 && hexDigit <= 102) {
-        // a..f
-        val += (hexDigit - 87) * (1 << (4 * (len - 1 - i)));
-      } else {
-        throw throw new FormatException("Bad hexadecimal value");
-      }
-    }
-
-    return val;
-  }
+  static int hexToInt(String hex) => int.parse(hex, radix: 16);
 
   static String convertToHexString(int r, int g, int b, [num a]) {
     String rHex = Color._numAs2DigitHex(Color._clamp(r, 0, 255));
     String gHex = Color._numAs2DigitHex(Color._clamp(g, 0, 255));
     String bHex = Color._numAs2DigitHex(Color._clamp(b, 0, 255));
     String aHex = (a != null) ?
         Color._numAs2DigitHex((Color._clamp(a, 0, 1) * 255).round()) : "";
 
     // TODO(terry) 15.toRadixString(16) return 'F' on Dartium not f as in JS.
     //             bug: <http://code.google.com/p/dart/issues/detail?id=2670>
@@ skipping 909 matching lines @@
   num get width => (left != null ? left : 0) + (right != null ? right : 0);
 
   /**
    * The total size of the vertical edges. Equal to [top] + [bottom], where
    * null is interpreted as 0px.
    */
   num get height => (top != null ? top : 0) + (bottom != null ? bottom : 0);
 }
 
 _mergeVal(x, y) => y != null ? y : x;