title: Floating Action Button doesn't work
body: <p>I've added floating action button to my app, and it app crashes with an error:</p>
  
  <pre><code>Error inflating class android.support.design.widget.FloatingActionButton
  </code></pre>
  
  <p>Button works well on Android 7(tested using Nexus 5 emulator, api 24 and 25), but doesn't work with API 23, or less. As i understood from the documentation, FAB should work fine with this version of Android. How can i fix this bug? Below is my FAB code:</p>
  
  <pre><code>&lt;android.support.design.widget.FloatingActionButton
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:src="@drawable/ic_add_black_48dp"
      android:layout_alignParentBottom="true"
      android:layout_alignParentEnd="true"
      android:layout_alignParentRight="true"
      android:layout_marginRight="16dp"
      android:layout_marginBottom="16dp"
      android:id="@+id/float_btn"
      android:backgroundTint="@color/category_family"
      app:fabSize="normal" /&gt;
  </code></pre>
  
  <p>And Gradle File:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  android {
      compileSdkVersion 23
      buildToolsVersion '25.0.3'
  
  defaultConfig {
      applicationId "com.example.android.miwok"
      minSdkVersion 15
      targetSdkVersion 23
      versionCode 1
      versionName "1.0"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'org.immutables:gson:2.5.3'
      compile 'com.android.support:appcompat-v7:23.3.0'
      compile 'com.android.support:support-v4:23.3.0'
      compile 'com.android.support:design:23.3.0'
      compile 'com.google.firebase:firebase-database:10.0.1'
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
      testCompile 'junit:junit:4.12'
  }
  
  
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>