Revert "enhance tests (mostly codegen)" temporarily

This reverts commit 95f9bcbacb.

compiler/tests/org/jetbrains/jet/codegen/TraitsTest.java

@@ -16,16 +16,7 @@
 
 package org.jetbrains.jet.codegen;
 
-import org.jetbrains.jet.lang.resolve.java.CompilerSpecialMode;
-
 public class TraitsTest  extends CodegenTestCase {
-
-    @Override
-    protected void setUp() throws Exception {
-        super.setUp();
-        createEnvironmentWithMockJdk(CompilerSpecialMode.JDK_HEADERS);
-    }
-
     @Override
     protected String getPrefix() {
         return "traits";