Fix Gradle plugin build with Gradle 5.0

* Due to 'improved POM support' introduced in 5.0, runtime dependencies
of the `compileOnly 'com.android.tools.build:gradle:...'` dependency
were no more transitively available. Add them manually;

* Add `!!` to usages of `resourcesDir`, which became nullable;

* Replace the dropped `classesDir` method usages with reflection;

libraries/tools/kotlin-gradle-plugin/build.gradle.kts

@@ -1,5 +1,4 @@
-import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
-import com.gradle.publish.PluginConfig
+
 import org.jetbrains.dokka.gradle.DokkaTask
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 import org.jetbrains.kotlin.pill.PillExtension
@@ -46,6 +45,9 @@ dependencies {
     compileOnly(project(":kotlin-scripting-compiler"))
 
     compileOnly("com.android.tools.build:gradle:2.0.0")
+    compileOnly("com.android.tools.build:gradle-core:2.0.0")
+    compileOnly("com.android.tools.build:builder:2.0.0")
+    compileOnly("com.android.tools.build:builder-model:2.0.0")
     compileOnly("org.codehaus.groovy:groovy-all:2.4.12")
     compileOnly(gradleApi())
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/model/builder/KotlinModelBuilder.kt

@@ -95,7 +95,7 @@ class KotlinModelBuilder(private val kotlinPluginVersion: String, private val an
                     kotlinSourceSet.kotlin.srcDirs,
                     javaSourceSet.resources.srcDirs,
                     destinationDir,
-                    javaSourceSet.output.resourcesDir,
+                    javaSourceSet.output.resourcesDir!!,
                     createCompilerArguments()
                 )
             } else null

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/kotlinCompilationOutputs.kt

@@ -38,10 +38,10 @@ class KotlinWithJavaCompilationOutput(
         get() = compilation.javaSourceSet.output
 
     override val resourcesDir: File
-        get() = javaSourceSetOutput.resourcesDir
+        get() = javaSourceSetOutput.resourcesDir!!
 
     override var resourcesDirProvider: Any
-        get() = javaSourceSetOutput.resourcesDir
+        get() = javaSourceSetOutput.resourcesDir!!
         set(value) {
             javaSourceSetOutput.setResourcesDir(value)
         }