Allow overriding for DateTimePatternGenerator in CustomDateTimeFormatGenerator.

Change-Id: I3b64b9bd324d4ad9934a7a176e01b76b4891fa12
diff --git a/user/src/com/google/gwt/i18n/rebind/CustomDateTimeFormatGenerator.java b/user/src/com/google/gwt/i18n/rebind/CustomDateTimeFormatGenerator.java
index dd4145d..95c4181 100644
--- a/user/src/com/google/gwt/i18n/rebind/CustomDateTimeFormatGenerator.java
+++ b/user/src/com/google/gwt/i18n/rebind/CustomDateTimeFormatGenerator.java
@@ -96,7 +96,7 @@
     }
     // TODO(jat): runtime locales support
     GwtLocale gwtLocale = localeUtils.getCompileLocale();
-    DateTimePatternGenerator dtpg = new DateTimePatternGenerator(gwtLocale);
+    DateTimePatternGenerator dtpg = getDateTimePatternGenerator(gwtLocale);
     String packageName = targetClass.getPackage().getName();
     String className = targetClass.getName().replace('.', '_') + "_"
         + gwtLocale.getAsString();
@@ -141,4 +141,8 @@
     }
     return packageName + "." + className;
   }
+
+  protected DateTimePatternGenerator getDateTimePatternGenerator(GwtLocale gwtLocale) {
+    return new DateTimePatternGenerator(gwtLocale);
+  }
 }