title: Android App stops when Button has drawable<xyz>
body: <p>I have a problem adding an icon to a button either left of text or above.
  This is my test scenario:</p>
  
  <p>My app already has a main activity with a button to start the newly added test activity.</p>
  
  <p>I add an "Empty Activity" to my app, place a button on it and start the app, the activity shows, everything's fine.</p>
  
  <p>Now I set the button's 'drawableTop="@drawable/ic_add_circle' where ic_add_circle contains the Android Studio material icon "add circle outline" in 24x24dp.</p>
  
  <p>In the design editor everything look fine, but when I start my app and try to show the activity, the app stops immediately. 
  I tried this with drawableTop, Left, Right, Bottom - always the same.
  What am i doing wrong?</p>
  
  <p>This is the Activity's xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="me.myself.i.test.myActivity"&gt;
  &lt;Button
      android:id="@+id/button4"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_marginLeft="16dp"
      android:layout_marginTop="16dp"
      android:drawableTop="@drawable/ic_add_circle"
      android:text="Button"
      app:layout_constraintLeft_toLeftOf="parent"
      app:layout_constraintTop_toTopOf="parent" /&gt;
  </code></pre>
  
  <p></p>
  
  <p>... the icon</p>
  
  <pre><code>&lt;vector xmlns:android="http://schemas.android.com/apk/res/android"
      android:width="24dp"
      android:height="24dp"
      android:viewportWidth="24.0"
      android:viewportHeight="24.0"&gt;
  &lt;path
      android:fillColor="#FF000000"
      android:pathData="M13,7h-2v4L7,11v2h4v4h2v-4h4v-2h-4L13,7zM12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM12,20c-4.41,0 -8,-3.59 -8,-8s3.59,-8 8,-8 8,3.59 8,8 -3.59,8 -8,8z"/&gt;
  &lt;/vector&gt;
  </code></pre>
  
  <p>... and the java code</p>
  
  <pre><code>package me.myself.i.test;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  
  public class myActivity extends AppCompatActivity {
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.my_activity);
      }
  }
  </code></pre>