Pass kotlinc sources in for SealedClassTest

If not the test will fail. Additionally, kotlinc will wait for input
so the tests will never finish.

Change-Id: I7306aa6483865989afb73182343435dda93569dd
diff --git a/src/test/java/com/android/tools/r8/KotlinTestBase.java b/src/test/java/com/android/tools/r8/KotlinTestBase.java
index c112fb9..848c483 100644
--- a/src/test/java/com/android/tools/r8/KotlinTestBase.java
+++ b/src/test/java/com/android/tools/r8/KotlinTestBase.java
@@ -91,6 +91,7 @@
   }
 
   public static KotlinCompileMemoizer getCompileMemoizer(Collection<Path> sources) {
+    assert sources.size() > 0;
     return new KotlinCompileMemoizer(sources);
   }
 
diff --git a/src/test/java/com/android/tools/r8/kotlin/sealed/SealedClassTest.java b/src/test/java/com/android/tools/r8/kotlin/sealed/SealedClassTest.java
index cfe38a7..6b70ca2 100644
--- a/src/test/java/com/android/tools/r8/kotlin/sealed/SealedClassTest.java
+++ b/src/test/java/com/android/tools/r8/kotlin/sealed/SealedClassTest.java
@@ -47,7 +47,8 @@
     this.parameters = parameters;
   }
 
-  private static KotlinCompileMemoizer compilationResults = getCompileMemoizer();
+  private static final KotlinCompileMemoizer compilationResults =
+      getCompileMemoizer(getKotlinSources());
 
   private static Collection<Path> getKotlinSources() {
     try {