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();
-
-// Flat cons strings can point to a thin string.
-
-function get_cons_thin_string(a, b) {
-  // Make a ConsString.
-  var s = a + b;
-  // Flatten it.
-  s.endsWith("a");
-  // Internalize the first part.
-  var o = {};
-  o[s];
-  return s;
-}
-
-var s = get_cons_thin_string("__________", "@@@@@@@@@@a");
-s.match(/.*a/);
-assertEquals("________", s.substring(0, 8));
-
-function cc1(s) {
-  assertEquals(95, s.charCodeAt(0));
-  assertEquals(95, s.codePointAt(0));
-}
-cc1(s);
-cc1(s);
-%OptimizeFunctionOnNextCall(cc1);
-cc1(s);
-
-// Sliced strings can have a thin string as their parent.
-
-function get_sliced_thin_string(a, b) {
-  // Make a long thin string.
-  var s = a + b;
-  // Slice a substring out of it.
-  var slice = s.substring(0, 20);
-  // Make the original string thin.
-  var o = {};
-  o[s];
-  return slice;
-}
-
-var t = get_sliced_thin_string("abcdefghijklmnopqrstuvwxyz",
-                               "abcdefghijklmnopqrstuvwxyz");
-assertEquals("abcdefghijklmnopqrst", decodeURI(t));
-
-function cc2(s) {
-  assertEquals(97, s.charCodeAt(0));
-  assertEquals(97, s.codePointAt(0));
-}
-cc2(t);
-cc2(t);
-%OptimizeFunctionOnNextCall(cc2);
-cc2(t);