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..9bb8734829660d2d61ab22defe7111bd51b3bee1 100644
--- a/sdk/lib/crypto/crypto_base.dart
+++ b/sdk/lib/crypto/crypto_base.dart
@@ -124,12 +124,30 @@ 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'.
+   * base64 encoded string optionally broken up in to lines of 76

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

Try to have the first line of the doc explain the high-level operation of the
method, as a single sentence. This is the line that will be initially visible in
the generated DartDoc.

Other general rules for dartdoc: Avoid abbreviations ("characters", not
"chars"). Use full sentences (you do).

In this case, for example: 
/**
 * 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.
 *
 * It is an error if both [urlSafe] and [addSeparator] are true.
 *
 * Based on RFC 4648 - http://tools.ietf.org/html/tfc4648
 */

[mdakin1, 2013/03/21 15:27:15]

Done,
Instead of making it an error, should we just ignore the addSeparator if urlSafe
is true?

+   * chars separated by '\r\n'.
+   * Optionally generates url and filename safe encoding if [urlSafe]
+   * is set to true.
+   * Based on RFC 4686 http://tools.ietf.org/html/rfc4648

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

4686 -> 4648

[mdakin1, 2013/03/21 15:27:15]

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 base64 encoded String into list of bytes. Decoder ignores \r\n

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

base64 -> Base64.
into list -> into a list
New paragraph after "bytes.".

[mdakin1, 2013/03/21 15:27:15]

Done.

+   * from input. By default also ignores all illegal chars unless

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

\r\n from inpu -> "\r\n" sequences in the input.
By default also -> By default it also
chars -> characters.

[mdakin1, 2013/03/21 15:27:15]

Done.

+   * [ignoreErrors] is false.

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

New paragraph here. Dartdoc flows like HTML, so the newline here won't matter,
but a second one will start a new paragraph.

[mdakin1, 2013/03/21 15:27:15]

Done.

+   * Accepts both url safe and unsafe base64 encoded strings.

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

url -> URL
base64->Base 64 (just my preference, stands out more if capitalized).

[mdakin1, 2013/03/21 15:27:15]

Done.

+   * Returns empty list if [input] is null.

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

Returns empty -> Returns an empty

[mdakin1, 2013/03/21 15:27:15]

Done.

+   * Based on RFC 4686 http://tools.ietf.org/html/rfc4648

[Lasse Reichstein Nielsen, 2013/03/21 14:06:38]

4686 -> 4648

[mdakin1, 2013/03/21 15:27:15]

Done.

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