Revert of Internalize strings in-place

test/mjsunit/thin-strings.js

-// Copyright 2016 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: --allow-natives-syntax
-
-function get_thin_string(a, b) {
-  var str = a + b;  // Make a ConsString.
-  var o = {};
-  o[str];  // Turn it into a ThinString.
-  return str;
-}
-
-var str = get_thin_string("foo", "bar");
-
-var re = /.o+ba./;
-assertEquals(["foobar"], re.exec(str));
-assertEquals(["foobar"], re.exec(str));
-assertEquals(["foobar"], re.exec(str));
-
-function CheckCS() {
-  assertEquals("o", str.substring(1, 2));
-  assertEquals("f".charCodeAt(0), str.charCodeAt(0));
-  assertEquals("f", str.split(/oo/)[0]);
-}
-CheckCS();
-%OptimizeFunctionOnNextCall(CheckCS);
-CheckCS();
-
-function CheckTF() {
-  try {} catch(e) {}  // Turbofan.
-  assertEquals("o", str.substring(1, 2));
-  assertEquals("f".charCodeAt(0), str.charCodeAt(0));
-  assertEquals("f", str.split(/oo/)[0]);
-}
-CheckTF();
-%OptimizeFunctionOnNextCall(CheckTF);
-CheckTF();