Perform minor cleanup in ShadowIcon.java

Switch to using the two-argument directlyOn and add @HiddenApi
annotation.

robolectric-shadows/shadows-core/src/main/java/org/robolectric/shadows/ShadowIcon.java

@@ -4,6 +4,7 @@
 import android.graphics.drawable.Icon;
 import android.net.Uri;
 import android.os.Build;
+import org.robolectric.annotation.HiddenApi;
 import org.robolectric.annotation.Implementation;
 import org.robolectric.annotation.Implements;
 import org.robolectric.annotation.RealObject;
@@ -21,38 +22,45 @@ public class ShadowIcon {
   @RealObject
   private Icon realIcon;
 
+  @HiddenApi
   @Implementation
   public int getType() {
-    return directlyOn(realIcon, Icon.class, "getType");
+    return directlyOn(realIcon, Icon.class).getType();
   }
 
+  @HiddenApi
   @Implementation
   public int getResId() {
-    return directlyOn(realIcon, Icon.class, "getResId");
+    return directlyOn(realIcon, Icon.class).getResId();
   }
 
+  @HiddenApi
   @Implementation
   public Bitmap getBitmap() {
-    return directlyOn(realIcon, Icon.class, "getBitmap");
+    return directlyOn(realIcon, Icon.class).getBitmap();
   }
 
+  @HiddenApi
   @Implementation
   public Uri getUri() {
-    return directlyOn(realIcon, Icon.class, "getUri");
+    return directlyOn(realIcon, Icon.class).getUri();
   }
 
+  @HiddenApi
   @Implementation
   public int getDataLength() {
-    return directlyOn(realIcon, Icon.class, "getDataLength");
+    return directlyOn(realIcon, Icon.class).getDataLength();
   }
 
+  @HiddenApi
   @Implementation
   public int getDataOffset() {
-    return directlyOn(realIcon, Icon.class, "getDataOffset");
+    return directlyOn(realIcon, Icon.class).getDataOffset();
   }
 
+  @HiddenApi
   @Implementation
   public byte[] getDataBytes() {
-    return directlyOn(realIcon, Icon.class, "getDataBytes");
+    return directlyOn(realIcon, Icon.class).getDataBytes();
   }
 }