Make HttpDateTime public (but hidden), so the rest of us can use it

instead of SimpleDateTime (which is super slow).

core/java/android/webkit/HttpDateTime.java

@@ -23,7 +23,8 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 
-class HttpDateTime {
+/** {@hide} */
+public final class HttpDateTime {
 
     /*
      * Regular expression for parsing HTTP-date.