Better documentation on Sets and Maps, and more.

runtime/lib/string_patch.dart

Index: runtime/lib/string_patch.dart
diff --git a/runtime/lib/string_patch.dart b/runtime/lib/string_patch.dart
index 0707a5fdaa91fdfe3aadb824fb138661470385bc..3cdb2a12d37a6433974dcb85c6853c66726a900f 100644
--- a/runtime/lib/string_patch.dart
+++ b/runtime/lib/string_patch.dart
@@ -267,9 +267,12 @@ class _StringBase {
 
   bool contains(Pattern pattern, [int startIndex = 0]) {
     if (pattern is String) {
+      if (startIndex < 0 || startIndex > this.length) {
+        throw new RangeError.range(startIndex, 0, this.length);
+      }
       return indexOf(pattern, startIndex) >= 0;
     }
-    return pattern.allMatches(this.substring(startIndex)).iterator.moveNext();
+    return pattern.allMatches(this.substring(startIndex)).isNotEmpty;
   }
 
   String replaceFirst(Pattern pattern, String replacement) {