title: Error:Could not find property 'assembleDebug' on project ':app'
body: <p>I am using <code>'com.android.tools.build:gradle:2.2.0-alpha6'</code> and Android Studio 2.2 Preview 6. The build runs perfectly fine on Gradle 2.1.0, but to enable instant run it asks me to update Gradle plugin.</p>
  
  <p>On updating Gradle plugin, the build shows <code>"Error:Could not find property 'assembleDebug' on project ':app'"</code>. I already tried cleaning <code>.gradle</code> and <code>.idea</code> and reloading the project, but nothing works.</p>
  
  <p>Please help.</p>