Fix warning check in tests:

* Fix the regex that could not actually find warnings
* Suppress an unused parameter warning in the test project
* Add allWarningsAsErrors to ExecutionStrategyIT

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

@@ -299,7 +299,7 @@ abstract class BaseGradleIT {
     }
 
     fun CompiledProject.assertNoWarnings() {
-        val warnings = "w: .*$".toRegex().findAll(output).map { it.groupValues[0] }
+        val warnings = "w: .*".toRegex().findAll(output).map { it.groupValues[0] }
 
         if (warnings.any()) {
             val message = (listOf("Output should not contain any warnings:") + warnings).joinToString(SYSTEM_LINE_SEPARATOR)

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

@@ -7,7 +7,7 @@ import java.io.File
 
 class ExecutionStrategyJsIT : ExecutionStrategyIT() {
     override fun setupProject(project: Project) {
-        project.setupWorkingDir()
+        super.setupProject(project)
         val buildGradle = File(project.projectDir, "app/build.gradle")
         buildGradle.modify { it.replace("apply plugin: \"kotlin\"", "apply plugin: \"kotlin2js\"") +
                 "\ncompileKotlin2Js.kotlinOptions.outputFile = \"web/js/out.js\"" }
@@ -62,6 +62,10 @@ open class ExecutionStrategyIT : BaseGradleIT() {
     }
 
     protected open fun setupProject(project: Project) {
+        project.setupWorkingDir()
+        File(project.projectDir, "app/build.gradle").appendText(
+                "\ntasks.withType(org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile).all { kotlinOptions.allWarningsAsErrors = true }"
+        )
     }
 
     protected open fun CompiledProject.checkOutput() {

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

@@ -1,3 +1,4 @@
 package foo
 
-fun f(fn: (x: Int)->Unit) {}
+@Suppress("unused_parameter")
+fun f(fn: (x: Int)->Unit) { }