enhance tests (mostly codegen)

* drop dependency on stdlib/alt-headers in the most tests
* assign to myEnvironment at most once in JetLiteFixture
* more tests do not compile runtime

compiler/tests/org/jetbrains/jet/runtime/JetNpeTest.java

@@ -22,6 +22,14 @@ import org.jetbrains.jet.codegen.CodegenTestCase;
 import java.lang.reflect.Method;
 
 public class JetNpeTest extends CodegenTestCase {
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        createEnvironmentWithMockJdk();
+    }
+
+
+
     public void testStackTrace () {
         try {
             Intrinsics.throwNpe();