Add base64 decoder and change existing base64 encoder.

sdk/lib/crypto/crypto_base.dart

Index: sdk/lib/crypto/crypto_base.dart
diff --git a/sdk/lib/crypto/crypto_base.dart b/sdk/lib/crypto/crypto_base.dart
index d1666b51ed9a7bafb0a5537301fb92a67b2577d5..20f434408ccc327259350de74ad9da4a2e2f8f9b 100644
--- a/sdk/lib/crypto/crypto_base.dart
+++ b/sdk/lib/crypto/crypto_base.dart
@@ -123,13 +123,45 @@ abstract class CryptoUtils {
   }
 
   /**
-   * Converts a list of bytes (for example a message digest) into a
-   * base64 encoded string optionally broken up in to lines of
-   * [lineLength] chars separated by '\r\n'.
+   * Converts a list of bytes into a Base 64 encoded string.
+   *
+   * The list can be any list of integers in the range 0..255,
+   * for example a message digest.
+   *
+   * If [addLineSeparator] is true, the resulting string will  be
+   * broken into lines of 76 characters, separated by "\r\n".
+   *
+   * If [urlSafe] is true, the result is URL and filename safe.
+   *
+   * If [usePadding] is false, No extra padding characters ('=') are
+   * appended to the output.
+   *
+   * Based on RFC 4648 http://tools.ietf.org/html/rfc4648

[floitsch, 2013/03/25 17:45:37]

nit: I think Markdown has a way to specify URLs. Not sure dartdoc supports it,
but would be nice if it did.

[mdakin1, 2013/03/26 09:52:17]

Done.

+   *
    */
-  static String bytesToBase64(List<int> bytes, [int lineLength]) {
-    return _CryptoUtils.bytesToBase64(bytes, lineLength);
+  static String bytesToBase64(List<int> bytes,
+                              {bool urlSafe : false,
+                               bool addLineSeparator : false}) {
+    return _CryptoUtils.bytesToBase64(bytes,
+                                      urlSafe,
+                                      addLineSeparator);
   }
+
+
+  /**
+   * Converts a Base 64 encoded String into list of bytes.
+   *
+   * Decoder ignores "\r\n" sequences from input. By default it also ignores
+   * all illegal characters unless [ignoreErrors] is false.
+   *
+   * Accepts both URL safe and unsafe Base 64 encoded strings.
+   *
+   * Based on RFC 4648 http://tools.ietf.org/html/rfc4648

[floitsch, 2013/03/25 17:45:37]

ditto.

[mdakin1, 2013/03/26 09:52:17]

Done.

+   */
+  static List<int> base64StringToBytes(String input, {bool ignoreErrors : true}) {
+    return _CryptoUtils.base64StringToBytes(input, ignoreErrors);
+  }
+
 }
 
 /**