13700 update flutter 1.9

android/build.gradle

@@ -1,12 +1,12 @@
 buildscript {
-  ext.kotlin_version = '1.2.40'
+  ext.kotlin_version = '1.3.61'
   repositories {
     google()
     jcenter()
   }
 
   dependencies {
-    classpath 'com.android.tools.build:gradle:3.1.1'
+    classpath 'com.android.tools.build:gradle:3.4.2'
     classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
   }
 }
@@ -17,17 +17,3 @@ allprojects {
     jcenter()
   }
 }
-
-rootProject.buildDir = '../build'
-subprojects {
-  project.buildDir = "${rootProject.buildDir}/${project.name}"
-  project.evaluationDependsOn(':app')
-}
-
-task clean(type: Delete) {
-  delete rootProject.buildDir
-}
-
-task wrapper(type: Wrapper) {
-  gradleVersion = '2.14.1'
-}