Fix some warnings in pub and pkg packages.

pkg/intl/lib/number_format.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.
 
 part of intl;
 /**
  * Provides the ability to format a number in a locale-specific way. The
  * format is specified as a pattern using a subset of the ICU formatting
  * patterns.
  *
@@ skipping 457 matching lines @@
     format._positivePrefix = _parseAffix();
     var trunk = _parseTrunk();
     format._positiveSuffix = _parseAffix();
     // If we have separate positive and negative patterns, now parse the
     // the negative version.
     if (pattern.current == _NumberFormatParser._PATTERN_SEPARATOR) {
       pattern.moveNext();
       format._negativePrefix = _parseAffix();
       // Skip over the negative trunk, verifying that it's identical to the
       // positive trunk.
-      for (var each in _iterator(trunk)) {
+      for (var each in _iterable(trunk)) {
         if (pattern.current != each && pattern.current != null) {
           throw new FormatException(
               "Positive and negative trunks must be the same");
         }
         pattern.moveNext();
       }
       format._negativeSuffix = _parseAffix();
     } else {
       // If no negative affix is specified, they share the same positive affix.
       format._negativePrefix = format._positivePrefix + format._negativePrefix;
@@ skipping 224 matching lines @@
       default:
         return false;
     }
     trunk.write(ch);
     pattern.moveNext();
     return true;
   }
 }
 
 /**
+ * Returns an [Iterable] on the string as a list of substrings.
+ */
+Iterable _iterable(String s) => new _StringIterable(s);
+
+/**
  * Return an iterator on the string as a list of substrings.
  */
 Iterator _iterator(String s) => new _StringIterator(s);
 
+// TODO(nweiz): remove this when issue 3780 is fixed.
+/**
+ * Provides an Iterable that wraps [_iterator] so it can be used in a `for`
+ * loop.
+ */
+class _StringIterable extends Iterable<String> {
+  final Iterator<String> iterator;
+
+  _StringIterable(String s)
+      : iterator = _iterator(s);
+}
+
 /**
  * Provides an iterator over a string as a list of substrings, and also
  * gives us a lookahead of one via the [peek] method.
  */
 class _StringIterator implements Iterator<String> {
   String input;
   var index = -1;
   inBounds(i) => i >= 0 && i < input.length;
   _StringIterator(this.input);
   String get current => inBounds(index) ? input[index] : null;
 
   bool moveNext() => inBounds(++index);
   String get peek => inBounds(index + 1) ? input[index + 1] : null;
   Iterator<String> get iterator => this;
 }