Add simple test infrastructure for JS DCE

Add test infrastructure that allows to test handwritten JS
to test various small aspects of DCE, as opposed to box tests
which test kotlin stdlib + kotlin generated examples

generators/src/org/jetbrains/kotlin/generators/tests/GenerateTests.kt

@@ -144,6 +144,7 @@ import org.jetbrains.kotlin.j2k.AbstractJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.jps.build.*
 import org.jetbrains.kotlin.jps.build.android.AbstractAndroidJpsTestCase
 import org.jetbrains.kotlin.jps.incremental.AbstractProtoComparisonTest
+import org.jetbrains.kotlin.js.test.AbstractDceTest
 import org.jetbrains.kotlin.js.test.semantics.*
 import org.jetbrains.kotlin.jvm.compiler.*
 import org.jetbrains.kotlin.jvm.runtime.AbstractJvm8RuntimeDescriptorLoaderTest
@@ -1351,6 +1352,10 @@ fun main(args: Array<String>) {
         testClass<AbstractOutputPrefixPostfixTest> {
             model("outputPrefixPostfix/", pattern = "^([^_](.+))\\.kt$", targetBackend = TargetBackend.JS)
         }
+
+        testClass<AbstractDceTest> {
+            model("dce/", pattern = "(.+)\\.js", targetBackend = TargetBackend.JS)
+        }
     }
 
     testGroup("js/js.tests/test", "compiler/testData") {