Use minimal optimisation to slightly speed up the tests.

js/js.tests/test/org/jetbrains/k2js/test/utils/TranslationUtils.java

@@ -19,6 +19,7 @@ package org.jetbrains.k2js.test.utils;
 import com.google.dart.compiler.backend.js.ast.JsProgram;
 import com.intellij.openapi.project.Project;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.psi.JetFile;
 import org.jetbrains.k2js.facade.K2JSTranslator;
 import org.jetbrains.k2js.test.config.TestConfig;
@@ -36,6 +37,9 @@ public final class TranslationUtils {
     private TranslationUtils() {
     }
 
+    @Nullable
+    private static /*var*/ K2JSTranslator translator = null;
+
     public static void translateFile(@NotNull Project project, @NotNull String inputFile,
                                      @NotNull String outputFile) throws Exception {
         translateFiles(project, Collections.singletonList(inputFile), outputFile);
@@ -43,9 +47,16 @@ public final class TranslationUtils {
 
     public static void translateFiles(@NotNull Project project, @NotNull List<String> inputFiles,
                                       @NotNull String outputFile) throws Exception {
-        K2JSTranslator translator = new K2JSTranslator(new TestConfig(project));
         List<JetFile> psiFiles = createPsiFileList(inputFiles, project);
-        JsProgram program = translator.generateProgram(psiFiles);
+        JsProgram program = getTranslator(project).generateProgram(psiFiles);
         K2JSTranslator.saveProgramToFile(outputFile, program);
     }
+
+    @NotNull
+    private static K2JSTranslator getTranslator(@NotNull Project project) {
+        if (translator == null) {
+            translator = new K2JSTranslator(new TestConfig(project));
+        }
+        return translator;
+    }
 }