added lox test files

lox.t/while/syntax.lox

@@ -0,0 +1,21 @@
+// Single-expression body.
+var c = 0;
+while (c < 3) print c = c + 1;
+// expect: 1
+// expect: 2
+// expect: 3
+
+// Block body.
+var a = 0;
+while (a < 3) {
+  print a;
+  a = a + 1;
+}
+// expect: 0
+// expect: 1
+// expect: 2
+
+// Statement bodies.
+while (false) if (true) 1; else 2;
+while (false) while (true) 1;
+while (false) for (;;) 1;