Fix ArrayList creation from Collection introduced in previous changeset

Change-Id: I90ec2a9fa11efa027299d638807bdfb737804af9
diff --git a/user/super/com/google/gwt/emul/java/util/ArrayList.java b/user/super/com/google/gwt/emul/java/util/ArrayList.java
index 209f92b..d5c200e 100644
--- a/user/super/com/google/gwt/emul/java/util/ArrayList.java
+++ b/user/super/com/google/gwt/emul/java/util/ArrayList.java
@@ -62,7 +62,7 @@
 
   public ArrayList(Collection<? extends E> c) {
     // Avoid calling overridable methods from constructors
-    array = (E[]) c.toArray();
+    ArrayHelper.insertTo(array, 0, c.toArray());
   }
 
   public ArrayList(int initialCapacity) {