extract method: ensure folded replacement uses correct names, ensure invalid elements are skipped (IDEA-157519)

java/java-tests/testData/refactoring/extractMethod/FoldedWithNestedExpressions.java

@@ -0,0 +1,7 @@
+class Test {
+  void h(int i, String[] s, String[] t) {
+    <selection>System.out.println(t[i]);
+    final String s1 = s[t[i].length()];</selection>
+    System.out.println(s1);
+  }
+}