Adding isNotEmpty property to collection and string.

runtime/lib/collection_patch.dart

Index: runtime/lib/collection_patch.dart
diff --git a/runtime/lib/collection_patch.dart b/runtime/lib/collection_patch.dart
index 1ddd5d91dfd69b01f37d2baa9d205544d679057d..6479ba2f9e5939e78505a545b5f3da6093b05b8b 100644
--- a/runtime/lib/collection_patch.dart
+++ b/runtime/lib/collection_patch.dart
@@ -109,6 +109,8 @@ patch class HashMap<K, V> {
   /* patch */ int get length => _hashTable._elementCount;
 
   /* patch */ bool get isEmpty => _hashTable._elementCount == 0;
+
+  /* patch */ bool get isNotEmpty => !isEmpty;
 }
 
 patch class HashSet<E> {
@@ -130,6 +132,8 @@ patch class HashSet<E> {
 
   /* patch */ bool get isEmpty => _table._elementCount == 0;
 
+  /* patch */ bool get isNotEmpty => !isEmpty;
+
   /* patch */ bool contains(Object object) => _table._get(object) >= 0;
 
   // Collection.
@@ -300,6 +304,8 @@ patch class LinkedHashMap<K, V> {
   /* patch */ int get length => _hashTable._elementCount;
 
   /* patch */ bool get isEmpty => _hashTable._elementCount == 0;
+
+  /* patch */ bool get isNotEmpty => !isEmpty;
 }
 
 patch class LinkedHashSet<E> extends _HashSetBase<E> {
@@ -320,6 +326,8 @@ patch class LinkedHashSet<E> extends _HashSetBase<E> {
 
   /* patch */ bool get isEmpty => _table._elementCount == 0;
 
+  /* patch */ bool get isNotEmpty => !isEmpty;
+
   /* patch */ bool contains(Object object) => _table._get(object) >= 0;
 
   /* patch */ void forEach(void action(E element)) {