Implement ES6 String.raw behind --harmony-templates

test/mjsunit/harmony/templates.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony-templates
 
 var num = 5;
 var str = "str";
 function fn() { return "result"; }
 var obj = {
@@ skipping 312 matching lines @@
   assertEquals(1, calls);
 })();
 
 
 (function testUTF16ByteOrderMark() {
   assertEquals("\uFEFFtest", `\uFEFFtest`);
   assertEquals("\uFEFFtest", eval("`\uFEFFtest`"));
 })();
 
 
+(function testStringRawAsTagFn() {
+  assertEquals("\\u0065\\`\\r\\r\\n\\ntestcheck",
+               String.raw`\u0065\`\r\r\n\n${"test"}check`);
+  assertEquals("\\\n\\\n\\\n", eval("String.raw`\\\r\\\r\n\\\n`"));
+  assertEquals("", String.raw``);
+})();
+
+
 (function testExtendedArrayPrototype() {
   Object.defineProperty(Array.prototype, 0, {
     set: function() {
       assertUnreachable();
     }
   });
   function tag(){}
   tag`a${1}b`;
 })();