Rewrite ProgressionUtil to Kotlin, move to "kotlin.internal"

Use reflection in ProgressionUtilTest instead of calling methods on the class
from the class path, because in the latter case we were just testing
ProgressionUtil from bootstrap runtime (which, presumably, always works
correctly since it's a bootstrap distribution)

With this change, compilable built-ins (under core/builtins/src) are fully
written in Kotlin

compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -1023,7 +1023,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
             v.load(incrementVar, incrementType);
 
             Type methodParamType = asmElementType.getSort() == Type.LONG ? Type.LONG_TYPE : Type.INT_TYPE;
-            v.invokestatic("jet/runtime/ProgressionUtil", "getProgressionFinalElement",
+            v.invokestatic("kotlin/internal/InternalPackage", "getProgressionFinalElement",
                            Type.getMethodDescriptor(methodParamType, methodParamType, methodParamType, methodParamType));
 
             finalVar = createLoopTempVariable(asmElementType);

compiler/tests/org/jetbrains/jet/ProgressionUtilTest.java

@@ -16,27 +16,47 @@
 
 package org.jetbrains.jet;
 
-import jet.runtime.ProgressionUtil;
-import org.junit.Test;
+import com.intellij.testFramework.UsefulTestCase;
+import org.jetbrains.jet.codegen.forTestCompile.ForTestCompileRuntime;
 
-import static junit.framework.Assert.assertEquals;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
 
-public class ProgressionUtilTest {
+public class ProgressionUtilTest extends UsefulTestCase {
     private static final int MAX = Integer.MAX_VALUE;
     private static final int MIN = Integer.MIN_VALUE;
 
-    private static void doTest(int start, int end, int increment, int expected) {
-        int actualInt = ProgressionUtil.getProgressionFinalElement(start, end, increment);
+    private Method intMethod;
+    private Method longMethod;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        ClassLoader classLoader = new URLClassLoader(new URL[] {ForTestCompileRuntime.runtimeJarForTests().toURI().toURL()}, null);
+        Class<?> progressionUtil = classLoader.loadClass("kotlin.internal.InternalPackage");
+        this.intMethod = progressionUtil.getMethod("getProgressionFinalElement", int.class, int.class, int.class);
+        this.longMethod = progressionUtil.getMethod("getProgressionFinalElement", long.class, long.class, long.class);
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        this.intMethod = null;
+        this.longMethod = null;
+        super.tearDown();
+    }
+
+    private void doTest(int start, int end, int increment, int expected) throws Exception {
+        Object actualInt = intMethod.invoke(null, start, end, increment);
         assertEquals(expected, actualInt);
 
-        long actualLong = ProgressionUtil.getProgressionFinalElement((long) start, (long) end, (long) increment);
-        assertEquals(expected, actualLong);
+        Object actualLong = longMethod.invoke(null, (long) start, (long) end, (long) increment);
+        assertEquals((long) expected, actualLong);
     }
 
     private static final int[] INTERESTING = new int[]{ MIN, MIN / 2, -239, -23, -1, 0, 1, 42, 239, MAX / 2, MAX };
 
-    @Test
-    public void testGetFinalElement() {
+    public void testGetFinalElement() throws Exception {
         // start == end
         for (int x : INTERESTING) {
             for (int increment : INTERESTING) if (increment != 0) {