Fix for 7301594 Html.toHtml creating potentially invalid html

Generate <p dir="rtl"> instead of <p dir=rtl>. The form with the quotes
is cleaner and will reduce warnings in apps that consume the output.

Change-Id: Ic9879c8c882c42079598b741e897a24415d96374

Author: raphlinus

core/java/android/text/Html.java

@@ -221,10 +221,10 @@ private static String getOpenParaTagWithDirection(Spanned text, int start, int e
                 false /* no info */);
         switch(paraDir) {
             case Layout.DIR_RIGHT_TO_LEFT:
-                return "<p dir=rtl>";
+                return "<p dir=\"rtl\">";
             case Layout.DIR_LEFT_TO_RIGHT:
             default:
-                return "<p dir=ltr>";
+                return "<p dir=\"ltr\">";
         }
     }