Fix JS compiler jar search

#KT-15127 fixed

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kotlin2JsGradlePluginIT.kt

@@ -3,6 +3,7 @@ package org.jetbrains.kotlin.gradle
 import org.jetbrains.kotlin.gradle.util.getFileByName
 import org.jetbrains.kotlin.gradle.util.modify
 import org.junit.Test
+import java.io.File
 
 class Kotlin2JsGradlePluginIT : BaseGradleIT() {
     @Test
@@ -79,7 +80,7 @@ class Kotlin2JsGradlePluginIT : BaseGradleIT() {
         val project = Project("kotlinBuiltins", "3.2")
 
         project.setupWorkingDir()
-        val buildGradle = project.projectDir.getFileByName("build.gradle")
+        val buildGradle = File(project.projectDir, "app").getFileByName("build.gradle")
         buildGradle.modify {
             it.replace("apply plugin: \"kotlin\"", "apply plugin: \"kotlin2js\"") +
                     "\ncompileKotlin2Js.kotlinOptions.outputFile = \"out/out.js\""

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlinBuiltins/app/build.gradle

@@ -0,0 +1,9 @@
+apply plugin: "kotlin"
+
+repositories {
+    mavenLocal()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlinBuiltins/build.gradle

@@ -6,13 +6,3 @@ buildscript {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
-
-apply plugin: "kotlin"
-
-repositories {
-    mavenLocal()
-}
-
-dependencies {
-    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlinBuiltins/settings.gradle

@@ -0,0 +1 @@
+include ':app'

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/compilerJarSearchingUtil.kt

@@ -35,9 +35,16 @@ private fun findKotlinCompilerJar(project: Project, compilerClassName: String):
 
     val entryToFind = compilerClassName.replace(".", "/") + ".class"
     val jarFromClasspath = project.classpathJars().firstOrNull { it.hasEntry(entryToFind) }
-    val compilerJar = jarFromClasspath
 
-    return compilerJar
+    return when {
+        jarFromClasspath != null ->
+            jarFromClasspath
+        project.parent != null ->
+            findKotlinCompilerJar(project.parent, compilerClassName)
+        else ->
+            null
+
+    }
 }
 
 private fun File.hasEntry(entryToFind: String): Boolean {