Set default text style in layoutlib as NORMAL

If a style doesn't specify text style (normal/bold/italic/bold-italic)
then default to normal instead of throwing an error.

Bug: http://b.android.com/61358
Change-Id: I0138c73807a5ff6e4d938a99ece3044333110aa1

tools/layoutlib/bridge/src/android/graphics/Typeface_Delegate.java

@@ -103,6 +103,9 @@ public final class Typeface_Delegate {
         if (familyName == null) {
             familyName = DEFAULT_FAMILY;
         }
+        if (style < 0) {
+            style = Typeface.NORMAL;
+        }
 
         Typeface_Delegate newDelegate = new Typeface_Delegate(familyName, style);
         if (sFontLoader != null) {