Better WebView present test

app/src/main/AndroidManifest.xml

@@ -11,9 +11,13 @@
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="com.android.vending.BILLING" />
 
+    <!-- https://developer.android.com/guide/topics/manifest/uses-feature-element#features-reference -->
     <uses-feature
         android:name="android.software.app_widgets"
         android:required="false" />
+    <uses-feature
+        android:name="android.software.webview"
+        android:required="false" />
 
     <application
         android:name=".ApplicationEx"

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -1513,7 +1513,9 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
 
         this.dp24 = Math.round(24 * context.getResources().getDisplayMetrics().density);
         this.theme = prefs.getString("theme", "light");
-        this.hasWebView = Helper.classExists("android.webkit.WebView");
+
+        PackageManager pm = context.getPackageManager();
+        this.hasWebView = pm.hasSystemFeature("android.software.webview");
     }
 
     private static final DiffUtil.ItemCallback<TupleMessageEx> DIFF_CALLBACK =

app/src/main/java/eu/faircode/email/Helper.java

@@ -187,15 +187,6 @@ public class Helper {
         return new DecimalFormat("@@").format(bytes / Math.pow(unit, exp)) + " " + pre + "B";
     }
 
-    static boolean classExists(String className) {
-        try {
-            Class.forName(className);
-            return true;
-        } catch (ClassNotFoundException ignored) {
-            return false;
-        }
-    }
-
     static Address myAddress() throws UnsupportedEncodingException {
         return new InternetAddress("marcel+fairemail@faircode.eu", "FairCode");
     }